The 2013

Corridor Capacity Report Published November 2013 Lynn Peterson Secretary of Transportation

The 12th edition of the annual Congestion Report

WSDOTrsquos comprehensive annual multi-modal analysis of state highway system performance

Table of Contents

Table of Contents

Executive Summary

Dashboard of Indicators

Introduction

Corridor Capacity Analysis I-5 central Puget Sound area I-405 central Puget Sound area SR 520 central Puget Sound area I-90 central Puget Sound area SR 167 central Puget Sound area I-5 south Puget Sound area I-5 and I-205 Vancouver area Marine highways - Washington State Ferries I-90 Spokane area MAP-21 and Results Washington

Statewide Indicators Statewide Congestion Indicators Factors Affecting Congestion

Throughput Productivity

Commute Trip Analysis Central Puget Sound area South Puget Sound area Vancouver area (Southwest Washington) Spokane area (Eastern Washington) Snoqualmie Pass

High Occupancy Vehicle Trip Analysis

3 Project Results 77

4 Tolling Operations Annual Report Active Traffic Management

78 80

5 Incident Response Annual Report 81

11 13

Before and After Analyses of Capacity Projects I-405 Corridor Improvement Program BampA Analysis

85 89

15 Table of Tables and Graphs 91 17 19

Publication Information 92

21 23 25 27 29 30

MAP-21 and Results Washington WSDOT has been proactive in working with the American Association of State Highway and Transportation Officials (AASHTO) and US Department of Ttansportation to propose performance measures for the Moving Ahead for Progress

31 in the 21st Century (MAP-21) federal law WSDOT supports 32 the inclusion of air quality congestion system performance 35 and capacity-related performance measures in MAP-21

37 Governor Jay Insleersquos strategic plan for Washington

41 42 57 61 63 64

state called Results Washington includes capacity-related transportation performance measures as well as measures for sustainable transportation and infrastructure and clean energy use WSDOT has been working closely with the Governorrsquos Office to propose indicators in these areas For more information about MAP-21 or Results Washington see p 30

65

List of contributors

Community Transit Bill Kalinowski Intercity Transit Dennis Bloom King County Metro Katie Chalmers Rachel VerBoort Puget Sound Regional Council Rebecca King Kelly McGourty Sound Transit Lisa Enns Jim Moore Amy Shatzkin Southwest Regional Transportation Council Bob Hart Spokane Transit Authority Karl Otterstrom Joel Soden STAR Lab Sa Xiao Washington State Transportation Center (TRAC) Mark Hallenbeck John Ishimaru Duane Wright

WSDOT Matt Beaulieu Mike Bernard Mike Bjordahl Bradley Bobbitt Daniela Bremmer Ken Burgstahler Dave Bushnell Paula Connelley Mike Clark Todd Daley Mark Eldridge Mike Ellis Vince Fairhurst Sreenath Gangula Hien Giang Manouchehr Goudarzi Matt Hanbey Monica Harwood Joe Irwin Annie Johnson Steve Kim Todd Lamphere Bill Legg Sarah Lowry Jim Mahugh Diane McGuerty Patricia Michaud Janarthanan Natarajan TJ Nedrow John Nisbet Kynan Patterson Charles Prestrud Trevor Skelton Tim Sexton Raymond Shank Joe St Charles Anna St Martin Stan Suchan Mike Villnave Alison Wallingford Pat Whittaker Anna Yamada Shuming Yan

in partnership with

2 | WSDOT 2013 Corridor Capacity Report

Executive Summary

Executive Summary

Congestion remained below pre-recession levels in 2012

Statewide congestion data for the past six years (2007 through 2012) indicate that 2009 was the least congested year for Washington drivers The statewide congestion indicators are still below pre-recession levels as the economy continues to rebound

In 2012 each person in the state was delayed in traffic for 4 hours and 30 minutes This means an average household of two commuters spent 9 extra hours of time on the road due to traffic This is 12 minutes lower than in 2010 when the per-person vehicle hours of delay on state highways was 4 hours and 42 minutes

The delay on state highways cost Washington citizens and businesses $780 million in 2012 This is roughly $115 per person For a household of two commuters this is $230 each year To put it in perspective this amount is equal to 60 gallons of gas ($384 per gallon) allowing the household to drive approximately 1500 miles at 25 miles per gallon

When miles traveled are averaged across the population it is as if each Washingtonian drove 8303 miles in 2012 of which 4578 were on the state highway system Even though this sounds like a lot the person-miles traveled in 2012 were actually lower than 2010 by 24 on all roadways and 31 on state highways

WSDOT introduces new multi-modal measures With this edition WSDOT introduces new performance measures and a new graphical display of information all with an emphasis on multi-modal and person-based metrics

The new measures include park and ride (PampR) lot utilization routinely congested highway segments greenhouse gas (GHG) emissions transit ridership and the costs of congestion for commuters

The graphical display shows key system performance information related to specific urban corridors all aligned with a map of the corridor

Park and ride lot utilization rates The PampR lot locations are presented on the map along with available spaces and percent occupied in a table to help tell the multi-modal system performance story The PampR lots primarily cater to transit services on the corridor - other PampR lots exist as well

Routinely congested highway segments For the first time WSDOT is presenting the routinely congested segments in graphical format on each of the corridors statewide (except I-90 in Spokane) The routinely congested segments are identified for morning and evening commutes by direction of travel length of congested segment in miles and duration of congestion in hours

Greenhouse gas emissions estimated for corridors The greenhouse gas emissions from vehicles on the 40 high-demand commute corridors in the central Puget Sound area totaled 12156 metric tons of carbon dioxide (CO2) each weekday in 2012 To put it in perspective this means an average commuter who drives in the central Puget Sound area is responsible for emitting more than 13 pounds of CO2 daily This estimate is for a subset of all Seattle area daily travel These emissions do not include principal arterials and surface streets in the area

Transit takes more than 43800 cars off the road daily In 2012 there were nearly 70600 daily transit riders during the peak commute periods on the high-demand corridors in the central Puget Sound area This took more than 43800 cars off the road which in turn avoided approximately 674700 pounds of CO2 emissions daily For example both buses and light rail from SeaTac to Seattle in the morning and from Seattle to SeaTac in the evening carried about 7600 and 10200 passengers each day during the peak periods respectively

Congestion costs increase on 21 corridors The cost of commute congestion (wasted time and gas) in the central Puget Sound area on the 40 high-demand commute routes increased on 21 decreased on 14 and remained the same on 5 commutes The largest reductions in commute congestion cost were on the SR 520 corridor Tolls were implemented in December 2011 and a significant number of commuters choose to drive alternate routes rather than pay the toll

For example the cost of congestion for commute trips on the I-5 corridor in 2012 for a round trip to and from work ranged from $400 to $1500 annually for each person The Everett-Seattle round trip had the highest commute congestion cost on this corridor in 2012

WSDOT 2013 Corridor Capacity Report | 3

-

Dashboard of Indicators

2013 Corridor Capacity Report Dashboard of Indicators Difference Dollar values are inflation-adjusted measured in 2012 dollars 2007 2008 2009 2010 2011 2012 lsquo10 vs lsquo12

Demographic and economic indicators

State population (thousands) 6525 6608 6672 6725 6768 6818 14

Gasoline price per gallon (annual average)1 $329 $364 $276 $317 $380 $384 208

Washington unemployment rate (annual) 46 54 94 99 92 82 -17

Washington real per person income2 $46265 $46706 $44386 $44369 $45197 $45941 35

Multi-modal performance measures

Drive alone commuting rate3 731 715 721 730 733 - -

Carpooling commuting rate3 114 122 113 105 102 - -

Public transit commuting rate3 54 55 59 55 56 - -

Transit ridership4 (in millions) 1952 2156 2101 2078 2130 - -

Washington State Ferries ridership4 (in millions) 241 233 225 226 223 - -

Bicycling and walking commuting rate3 41 45 43 44 42 - -

Statewide congestion indicators

Per person total vehicle miles traveled on all public roads state highways only

All public roads vehicle miles traveled (VMT) in billions 56964 55447 56461 57191 56965 56607 -10

All public roads per person VMT in miles 8730 8391 8462 8505 8417 8303 -24

State highways VMT in billions 31970 30742 31456 31764 31455 31214 -17

State highways per person VMT in miles 4900 4652 4714 4724 4648 4578 -31

Congestion on state highway system

Total state highway lane miles 18425 18500 18571 18630 18642 18659 02

Lane miles of state highway system congested 1032 962 966 1025 1007 1026 00

Percent of state highway system congested5 56 52 52 55 54 55 00

Per person total and cost of delay on state highways

Annual hours of per person delay on state highways6 54 53 42 47 48 45 -43

Total vehicle hours of delay in millions of hours6 351 348 281 316 325 309 -24

Cost of delay on state highways (2012 dollars)6 $931 $890 $721 $800 $821 $780 -24

Corridor specific congestion indicators (52 central Puget Sound area commutes)

Annual Maximum Throughput Travel Time Index (MT3I)7 145 1258 130 139 135 139 00

Number of commute routes with MT3I gt 17 46 418 43 45 44 44

WSDOT congestion relief projects

Number of completed Nickel and TPA mobility projects as 33 43 73 91 65 82of December 31 of each year (cumulative)

Cumulative project value (dollars in millions) $963 $1289 $2212 $2596 $2802 $3851 $1255

Data source Washington State Office of Financial Management Economic and Revenue Forecast Council Bureau of Economic Analysis US Department of Energy - Energy Information Administration Bureau of Labor Statistics ndash Consumer Price Index WSDOT State Highway Log US Census Bureau - American Community Survey National Transit Database

Notes WSDOTrsquos annual Congestion Report is renamed as the Corridor Capacity Report beginning with the 2013 publication Analysis in the 2013 Corridor Capacity Report examines 2010 and 2012 annual data 2007 is included to show pre-recession levels All dollar values are inflation-adjusted using the Consumer Price Index (CPI) 1 Gas prices are reported in 2012 dollars and represent yearly averages 2 Real per capita income is measured as total statewide personal income in 2012 dollars divided by state population 3 Based on one-year estimates from the American Community Survey commuting rates are of workers age 16 and older 4 Ridership means the number of boardings also called unlinked passenger trips 5 Based on below 70 of posted speed 6 Based on maximum throughput speed threshold (85 of posted speed) 7 MT3I greater than one means the commute route experiences congestion 8 2008 data not available for four of the 52 routes For more information see gray box in the 2009 Congestion Report p 15

4 | WSDOT 2013 Corridor Capacity Report Dashboard of Indicators

-1

18

Introduction

Introduction

WSDOTrsquos Corridor Capacity Report presents detailed analysis for current and baseline years The Corridor Capacity Reportrsquos detailed analysis shows where and how much congestion occurs and whether it has grown on state highways The report focuses on the most traveled commute routes in the urban areas of the state ie central and south Puget Sound areas Vancouver Spokane and the Tri-Cities area and elsewhere around the state where data is available WSDOT and University of Washington experts use a two-year span to more accurately identify changes and trends seen on the state highway system that may be missed by looking at a one-year comparison For the 2013 Corridor Capacity Report calendar year 2012 is the current analysis year data while 2010 data is the baseline for comparison Some exceptions were made to use 2011 data in place of 2010 due to data availability and data quality

This year WSDOT is introducing new performance metrics listed below along with the standard metrics

Key congestion performance measures

Measure Definition

WSDOTrsquos congestion measurement principles Use real-time measurements (rather than computer

models) whenever and wherever possible

Use maximum throughput as the basis for congestion measures

Distinguish between and measure both congestion due to incidents (non-recurrent) and congestion due to inadequate capacity (recurrent)

Show how reducing non-recurrent congestion from incidents will improve the travel time reliability

Demonstrate both long-term trends and short-toshyintermediate-term results

Communicate possible congestion fixes using an ldquoapples-to-applesrdquo comparison with the current situation For example ldquoIf the trip takes 20 minutes today how many minutes less will it be if WSDOT improves the interchangerdquo

Use ldquoplain Englishrdquo to describe measurements and results

NEW Commute congestion cost Cost due to wasted fuel and time associated with travel during congested conditions (speeds slower than 45 mph) that could have been spent productively elsewhere

NEW Greenhouse gas emissions The pounds of carbon dioxide (CO2) emitted during peak period commutes The per-person emissions per trip during peak periods The emissions avoided by use of transit services

NEW Transit ridership and used Ridership on buses light rail and commuter rail during the peak periods between commute route capacity origins and destinations Used capacity in percent of available seats that are used on transit already

serving commute routes

NEW Park and Ride capacity and use Number of parking spaces and percent of capacity used on an average annual weekday

NEW Routinely congested segments Sections of roadway where traffic demand reaches capacity on at least 40 of the weekdays annually

Average peak travel time The average travel time on a route during the peak five-minute interval for all weekdays of the calendar year

95th percentile reliable travel time Travel time with 95 certainty (ie on-time 19 out of 20 work days)

Maximum Throughput Travel Time Index (MTsup3I) The ratio of average peak travel time compared to maximum throughput speed travel time

Percent of days when speeds are Percent of days annually that observed speeds for one or more five-minute interval is less than 36 mph less than 36 mph (severe congestion) on key highway segments

Vehicle throughput Measures how many vehicles move through a highway segmentspot location in an hour

Lost throughput productivity Percentage of a highwayrsquos lost vehicle throughput due to congestion when compared to the maximum five-minute weekday flow rate observed at a particular location of the highway for that calendar year

Per person delay (other forms of delay The average total daily hours of delay per person based on the maximum throughput speed (85 of such as total delay) posted speed) measured annually for weekdays

Percent of the system congested Percent of total state highway lane miles that drop below 70 of the posted speed limit

Duration of congestion The time period in minutes when speeds fall below 45 mph

HOV lane reliability An HOV lane is deemed ldquoreliablerdquo as long as it maintains an average speed of 45 mph for 90 of the peak hour

Person throughput Measures how many people on average move through a highway segment during peak periods

Before and After analysis Before and After performance analysis of selected highway congestion relief projects and strategies

Average incident clearance time Operational measure defined as the time from notification of the incident until the last responder has left (Statewide) the scene for all incidents responded to by WSDOT Incident Response personnel statewide

WSDOT 2013 Corridor Capacity Report | 5

2012 greenhouse gas emissions factors for four categories of vehicles decline with increasing speed Carbon dioxide emissions in pounds of CO2 per vehicle mile traveled Speed in miles per hour

Introduction

Introduction

Measuring cost of congestion greenhouse gas emissions and transit

WSDOTrsquos new multi-modal system performance measures include commute congestion cost trip-based vehicle emissions transit usage park and ride lot capacity and use and locations that experience routine congestion

NEW WSDOT quantifies the congestion cost for individuals and commutes With the 2013 Corridor Capacity Report WSDOT is for the first time quantifying commute congestion cost at the individual commuter level to answer the question ldquohow much does congestion cost a daily commuterrdquo Commute congestion cost is based on the duration of congestion that represents the timeframe during which users can expect to travel at speeds below 45 mph (75 of posted speed) during their daily commute While daily commuters may build extra time and operating costs into their routines and budgets to account for traveling during congested periods congestion still represents costs lost opportunities and lost productivity that negatively affect individuals and society

Commute congestion cost = (Average travel time ndash Travel time at threshold speed) X Traffic volume within the duration of congestion X Cost of travel

Commute congestion cost is computed for every five-minute interval within the time that a particular commute is experiencing congestion This methodology underestimates commute congestion cost because it does not capture the periodic slowdowns (when speeds drop below 45 mph) briefly experienced during individual trips along the length of the commute Commute congestion cost can be estimated using the equation above

NEW WSDOT quantifies greenhouse gas emissions from commuters on central Puget Sound area routes WSDOTrsquos new metric captures the approximate pounds of carbon dioxide (CO2) emitted during a one-way commute trip Total emissions during the peak period are reported along with the emissions per person The per-person metric takes into consideration the average number of people in each vehicle in the single-occupancy vehicle lanes

CO2 emissions from vehicles are directly related to the speed at which the vehicle is traveling For speeds slower than 25 mph the emissions quickly escalate to more than five times as many pounds of CO2 per mile compared to at faster speeds (see example graph above right) However there is little variation in emissions per vehicle mile traveled between

Example greenhouse gas emissions factors for four categories of vehicles decline with increasing speed Carbon dioxide emissions in pounds of CO2 per vehicle mile traveled Speed in miles per hour 25

0

5

10

15

20

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75

Transit buses

Passenger car amp truck

Medium trucks

Heavy trucks

Data source Puget Sound Regional Council

Note Factors for 2012 restricted access urban roadways Emissions factors do not reflect relative emissions per person mile traveled by the different modes of transportation

35 and 65 mph the typical range of speeds on Washington highways Emissions also vary by the type of vehicles medium and large trucks emit more CO2 per mile than a typical passenger car Total emissions on a roadway during the peak period fluctuate more with the volume of vehicles on the roadway year to year than with the changes in average speed unless the average speeds are slower than 25 mph

CO2 emissions are computed for every five-minute interval within the morning or evening peak period applying emission factors based on the mix of trucks and passenger vehicles and the average speed during that time CO2

emissions can be estimated using the equation below

CO2 emissions during peak period = Sum for every 5 minutes during peak period ((Truck X Truck emission factor) + (1 - Truck) X Car emission factor) X Traffic volume within the 5-minute interval X Trip length)

Per person per trip CO2 emissions are calculated using the emissions during the peak period the average number of people in each vehicle in the single-occupancy vehicle lanes and the total traffic volume on the commute corridor during the peak period The per-person emissions can be estimated using the equation below

CO2 per person trip = (CO2 emissions during peak period) (Traffic volume during peak period X Average observed trip vehicle occupancy)

Emissions avoided by transit use are estimated with the following equation for commute trips during the peak periods

CO2 avoided = Number of transit riders during peak period X 062 SOV miles avoided per transit passenger mile X Trip length X 10 pound of CO2 per mile traveled

6 | WSDOT 2013 Corridor Capacity Report

Introduction

Introduction

WSDOTrsquos congestion measurement principles in action

NEW Quantifying the transit use along central Puget Sound area commute routes WSDOT for the first time measures system capacity across modes along the central Puget Sound area commute routes This includes the utilization of the HOV lanes compared to adjacent SOV lanes (see person-throughput analysis on p 66) and the capacity used on public transit services Sound Transit King County Metro and Community Transit provide public transportation services throughout the central Puget Sound area WSDOT aligned the bus light rail and Sounder commuter rail routes with the 40 peak period commute trips (see pp 49-52) WSDOT computed average daily transit statistics for each commute for ridership average load (percent of seats used) vehicle trips off the SOV lanes and greenhouse gas emissions avoided by transit ridership

NEW Park and ride lot use supports transit Park and ride (PampR) lots provide locations for a commuter to meet up with carpool or vanpool participants or to catch a bus to work if transit does not come close to their home WSDOT tracks the average percent of available space used PampR lots at or near capacity discourage potential transit users and ridesharers because they do not have a reliable place to park

NEW Routinely congested segments illustrate where demand exceeds capacity Specific sections of the urban highway system experience routine congestion due to constrained conditions WSDOT tracks how often demand exceeds capacity on the highway system and documents the frequency and length of time (duration) the route is congested This type of congestion is not related to incidents or collisions although such occurrences accentuate the regular congestion

NEW WSDOT expands commute trip analysis coverage around the state WSDOTrsquos 2013 Corridor Capacity Report expands the commute trip analysis coverage to include south Puget Sound and Vancouver area commute trips in addition to trips in the central Puget Sound and Spokane areas This brings the total to 82 commute trips analyzed statewide

WSDOT collects real-time traffic data WSDOT collects real-time data for all 82 commute routes in urban areas around the state including the central and south Puget Sound areas (52 and 20 routes respectively) the Vancouver area (8 routes) the Spokane area (2 routes) and on other highways statewide

In the central Puget Sound area alone data is collected from about 6800 loop detectors embedded in the pavement throughout 235 centerline miles (1300 lane miles) Similarly the south Puget Sound area has 128 active data sensors that stretch along 77 centerline miles (270 lane miles) Other urban areas of the state have loop detectors and other technologies used for traffic data collection WSDOT for the first time uses private sector speed data for Vancouver area commute trip analysis to complement the existing WSDOT data set

The data collected from these WSDOT loop detectors are quality controlled using a variety of software processes WSDOT uses this data to analyze system performance In tracking and communicating performance results WSDOT adheres to congestion measurement principles including the use of more accurate real-time data rather than modeled data and uses language and terminology that is meaningful to the public (ldquoplain Englishrdquo) See p 5 for a list of performance measures and principles

Measures that matter to drivers speed travel time and reliability Speed is a metric that carries importance not only with WSDOT but with the general public as well Measuring the time to get from point A to point B is one of the most easily understood congestion measures Travel time reliability also matters to commuters and businesses because it is important for people and goods to be on time all the time

WSDOTrsquos Corridor Capacity Report examines travel times on the 82 commute trips around the state with a particular focus on 40 high-demand routes in the central Puget Sound area Travel times for high occupancy vehicle (HOV) lanes along many of these same corridors are also reported

The metrics used in the commute trip analysis include the average peak travel time the 95th percentile reliable travel time the duration of congestion and the percent of weekdays when average travel speeds are below 36 mph The performance of an individual route compares data with the current analysis year to the baseline year

WSDOTrsquos previously published person-based measures (per capita for statewide measures) include per person vehicle miles traveled and per person hours of delay in traffic (statewide urban area and corridor based) along with the per person trip travel time on commute corridors

WSDOT expanded reliability analysis looks at a range

WSDOT 2013 Corridor Capacity Report | 7

Introduction

Introduction

How do WSDOTrsquos congestion performance measures work

of travel time percentiles in the 2009 Congestion Report This analysis allows WSDOT to examine travel time changes at a finer level of detail and better evaluate its operational strategies

Real-time travel times for key commute routes in central and south Puget Sound areas Spokane and Vancouver are available to the public and updated every 5 minutes on the WSDOT website at www wsdotwagovtrafficseattletraveltimes

Measuring vehicle miles traveled (VMT) WSDOT examines vehicle miles traveled (VMT) as a volume metric for each commute route VMT is calculated for peak hours for the commute routes and all-day VMT is reported as part of the statewide metric WSDOT examines factors such as the use of public transportation population change unemployment rates real personal income and fuel prices as they relate to volume and travel time changes

VMT allows WSDOT to quantify travel along a route Because traffic volumes vary along a route each locationrsquos traffic volume is multiplied by the representative length of the route and these values are added up to obtain a routersquos total VMT WSDOT uses this measure to better understand the number of trips taken on certain commute routes and the total miles traveled on state highways This helps WSDOT predict future demand and establish improvement needs

Traffic volume is a vehicle count at a given roadway location It is measured by a detector in each lane at the location WSDOT has loop detectors spaced at roughly half-mile intervals throughout the central Puget Sound area freeway network and at various locations on the highway system statewide

WSDOT uses maximum throughput to measure congestion performance To operate the highway system as efficiently as possible the speed at which the highest number of vehicles can move through a highway segment (maximum throughput) is more meaningful than posted speed as the basis of measurement WSDOT aims to provide and maintain a system that yields the most productivity and efficiency rather than a system that is free flowing but where fewer vehicles can pass through a segment during peak travel periods

Understanding maximum throughput An adaptation of the Understanding maximum throughput An adaptation speedvolume curve of the speedvolume curveMay 2010 weekday volume 6-10 am I-405 NB at 24th NE I-405 northbound at 24th NE 6-10 am weekdays volume in May 2010Speed limit 60 mph Maximum throughput speed ranges between Speed limit 60 mph Maximum throughput speed ranges between70 and 85 of posted speed 70-85 of posted speed

When few vehicles use a70 mph highway they can all travel

0 mph

10 mph

20 mph

30 mph

40 mph

50 mph

60 mph near the speed limit

Maximum throughput

As still more vehicles use a highway all traffic slows and capacitydecreases

If more vehicles use a highway traffic slows but capacity remains high

If too many vehicles usea highway congestion greatly reduces capacity

0 500 1000 1500 2000 2500 Volume of vehicles per hour per lane

Data source WSDOT Northwest Region Traffic Office

Maximum throughput is achieved when vehicles travel at speeds between 42 and 51 mph (roughly 70 to 85 of a posted 60 mph speed) At maximum throughput speeds highways are operating at peak efficiency because more vehicles are passing through the segment than at posted speeds This happens because drivers at maximum throughput speeds can safely travel with a shorter distance between vehicles than they can at posted speeds

Maximum throughput speeds vary from one highway segment to the next depending on prevailing roadway design (roadway alignment lane width slope shoulder width pavement conditions presence or absence of median barriers) and traffic conditions (traffic composition conflicting traffic movements heavy truck traffic etc) The maximum throughput speed is not static and can change over time as conditions change Ideally maximum throughput speeds for each highway segment should be determined through comprehensive traffic studies and validated by field surveys For surface arterials (interrupted flow facilities) maximum throughput speeds are difficult to predict because they are influenced by interruptions in flow due to the conflicting traffic movements at intersections

WSDOT uses the maximum throughput standard as a basis for measurement to assess travel delay relative to a highwayrsquos most efficient condition at maximum throughput speeds (85 of posted speed) For more information on changes in travel delay performance please see pp 42-64

8 | WSDOT 2013 Corridor Capacity Report

Introduction

Introduction

WSDOT thresholds for system efficiency maximum throughput

WSDOT also uses maximum throughput as a basis for evaluating the system through the following measures

Total delay and per person delay

Percent of the system that is delayed and congested

Lost throughput productivity

Maximum Throughput Travel Time IndexmdashMT3I (for a more detailed discussion see p 46)

Duration of the congested period

Commute congestion cost

Measuring per person delay and total delay Delay can be measured at various speed thresholds such as free flow speed posted speed or maximum throughput speeds WSDOT uses maximum throughput speeds rather than free flow or posted speeds to measure delay relative to the highwayrsquos most efficient operating condition WSDOT measures travel delay statewide and on five major commute corridors in the central Puget Sound area In addition to measuring total hours of delay WSDOT also evaluates annual per person delay and the cost of delay to drivers and businesses

Measuring the percentage of the highway system that is delayed This measure allows WSDOT to assess the percentage of its system that is operating below maximum throughput speed creating delay for the traveling public The metric is

calculated for an average weekday by dividing the number of lane miles where speeds drop below 85 of posted speeds by total lane miles It allows differentiation between delayed lane miles in urban and rural areas of the state

Measuring the percentage of the highway system that is congested This measure allows WSDOT to evaluate what percentage of the system that the agency manages is congested It is calculated for an annual average weekday by dividing the number of lane miles where speeds drop below 70 of posted speeds by total lane miles This measure also differentiates between the portion of congested lane miles in urban versus rural areas of the state

Evaluating vehicle throughput productivity Highways are engineered to move specific volumes of vehicles based on the number of lanes and other design aspects Highways are not necessarily operating at their maximum efficiency when all vehicles are moving at 60 mph (the typical urban highway posted speed limit in Washington) As congestion increases speeds decrease and fewer vehicles pass through the corridor Throughput productivity may decline from a maximum of about 2000 vehicles per hour per lane traveling at speeds between 42 and 51 mph (100 efficiency) to as low as 700 vehicles per hour per lane (35 efficiency) at speeds less than 30 mph

WSDOT state highway speed thresholds for congestion measurement

Measure Threshold Description

Posted speed 60 mph Vehicles are moving through a highway segment at the posted speed but to travel safely at higher speeds and allow sufficient stopping distance drivers must maintain more space between vehicles Fewer vehicles can pass through the segment in a given amount of time and the segment is not operating at maximum efficiency

Maximum throughput speed (optimal flow speed)

70-85 of posted speed (about 42-51 mph)

Vehicles are moving slower than the posted speed and the number of vehicles moving through the highway segment is higher These speed conditions enable the segment to reach its maximum productivity in terms of vehicle volume and throughput (based on the speedvolume curve) This threshold range is used for highway system deficiency analysis

Duration of congested period (urban commute routes)

Duration of time vehicle speeds drop below 75 of posted speeds (45 mph)

The average weekday peak time period (in minutes) when average vehicle speeds drop below 75 of posted speeds (about 45 mph) Drivers have less than optimal spacing between cars and the number of vehicles that can move through a highway segment is reduced The highway begins to operate less efficiently under these conditions than at maximum throughput

Percent of state highway system delayed

Less than 85 of posted speeds

Percent of total state highway lane miles that drop below 85 of the posted speed limit

Percent of state highway system congested

Less than 70 of posted speeds

Percent of total state highway lane miles that drop below 70 of the posted speed limit

Severe congestion

Less than 60 of posted speed (less than 36 mph)

Speeds and spacing between vehicles continue to decline on a highway segment and highway efficiency operates well below maximum productivity

WSDOT 2013 Corridor Capacity Report | 9

Introduction

Introduction

Measuring per person delay vehicle throughput reliability

Measuring travel time reliability WSDOT uses the 95th percentile reliable travel time as its key reliability metric for the 82 commute trips monitored statewide Travel time reliability is measured in percentiles For example 95th percentile travel times track the amount of time a traveler will need to plan in order to be on time 95 of the time (19 of 20 weekday trips) 80th percentile travel times will ensure the traveler is on time four out of five weekday trips A benefit to using percentile measures is they are not affected by outlier values generally the longest travel times Using a range of percentiles ndash from the 50th (median) to the 95th ndash allows WSDOT to track changes in reliable travel times over the years at a finer level in order to evaluate operational improvements more accurately Changes in the 80th and 90th percentiles are likely to represent travel times that are the result of routine incidents and other factors that the agency can influence with

5

5

90 405

167

512

3

305

104

16

520

522

9

203

202

2

2

18

525

Seattle Bellevue

Everett

Tacoma

Renton

Kent

Auburn

Puyallup

Lakewood

Federal Way

Mukilteo

Poulsbo

Bremerton

Purdy

Fife

Redmond

509

Pierce County

Pierce County Kitsap County

King County

King County

Snohomish County

Kitsap Peninsula

Vashon Island

BainbridgeIsland

PugetSound

Lake Washington

WhidbeyIsland

Sea-Tac Intrsquol Airport

Tacoma Narrows Bridge

167

Snoh

omish

County

Island

County

5

104

3

Freeway HOV amp HOT Lane System

HOV lanes operate 24 hours HOV lanes operate 24 hours 3+ HOV lanes operate 5 am - 7 pm HOV lanes in Reversible Express Lane Roadway (variable hours) HOT lanes operate 5 am - 7 pm Construction funded Construction unfunded or partially funded Direct Access Ramps ndash Open Direct Access Ramps ndash Open(Transit Only) Direct Access Ramps ndash Future

NOTE HOV lanes require two or morepeople (2+) unless otherwise notedHours of operation are for all seven daysof the week

T

T

Freeway HOV and HOT lane systems in the greater Puget Sound area

10 | WSDOT 2013 Corridor Capacity Report

operational strategies See pp 46-48 for detailed reliability data and pp 78-84 for more on operational strategies such as tolling Active Traffic Management Intelligent Transportation Systems (ITS) and Incident Response

WSDOT examines high occupancy vehicle (HOV) trip performance WSDOT uses several measures to evaluate HOV trip performance WSDOT and the Puget Sound Regional Council (PSRC) adopted a reliability standard for HOV lanes which states that for 90 of the peak hour HOV lanes should maintain an average speed of 45 mph This is the basis for WSDOTrsquos HOV reliability measure WSDOT also measures person throughput to gauge the effectiveness of HOV lanes in carrying more people compared to single occupancy vehicle (SOV) lanes and reports HOV trip travel times compared to SOV trip travel times

The map at left depicts the HOV and HOT lane system in the Puget Sound area About 310 lane-miles of the planned 320-mile Puget Sound area HOV network have been completed More information about the HOV lane network can be found starting on p 65 or at httpwwwwsdotwagovhov

Using Before and After analyses to review project performance As of June 30 2013 WSDOT completed 344 out of 421 projects funded by the 2003 and 2005 gas tax packages of which 91 were congestion relief projects To measure how well these investments are mitigating congestion WSDOT has implemented Before and After project studies to analyze impacts on travel times and delay On highway segments without in-pavement loop detectors data is collected using automated license plate recognition (ALPR) cameras blue tooth readers or moving test vehicles Before and After performance evaluations are performed on key congestion relief projects to evaluate the benefits of projects that improve system efficiency See pp 85-90

Quantifying Incident Response benefits WSDOT uses several measures to evaluate the performance of its Incident Response (IR) program Beginning in the 2011 Congestion Report WSDOT quantifies the annual economic benefits provided by the IR program For details on the IR program and how it helps alleviate non-recurrent congestion see pp 81-84

Table of Contents

Table of Contents

Executive Summary

Dashboard of Indicators

Introduction

Corridor Capacity Analysis I-5 central Puget Sound area I-405 central Puget Sound area SR 520 central Puget Sound area I-90 central Puget Sound area SR 167 central Puget Sound area I-5 south Puget Sound area I-5 and I-205 Vancouver area Marine highways - Washington State Ferries I-90 Spokane area MAP-21 and Results Washington

Statewide Indicators Statewide Congestion Indicators Factors Affecting Congestion

Throughput Productivity

Commute Trip Analysis Central Puget Sound area South Puget Sound area Vancouver area (Southwest Washington) Spokane area (Eastern Washington) Snoqualmie Pass

High Occupancy Vehicle Trip Analysis

3 Project Results 77

4 Tolling Operations Annual Report Active Traffic Management

78 80

5 Incident Response Annual Report 81

11 13

Before and After Analyses of Capacity Projects I-405 Corridor Improvement Program BampA Analysis

85 89

15 Table of Tables and Graphs 91 17 19

Publication Information 92

21 23 25 27 29 30

MAP-21 and Results Washington WSDOT has been proactive in working with the American Association of State Highway and Transportation Officials (AASHTO) and US Department of Ttansportation to propose performance measures for the Moving Ahead for Progress

31 in the 21st Century (MAP-21) federal law WSDOT supports 32 the inclusion of air quality congestion system performance 35 and capacity-related performance measures in MAP-21

37 Governor Jay Insleersquos strategic plan for Washington

41 42 57 61 63 64

state called Results Washington includes capacity-related transportation performance measures as well as measures for sustainable transportation and infrastructure and clean energy use WSDOT has been working closely with the Governorrsquos Office to propose indicators in these areas For more information about MAP-21 or Results Washington see p 30

65

List of contributors

Community Transit Bill Kalinowski Intercity Transit Dennis Bloom King County Metro Katie Chalmers Rachel VerBoort Puget Sound Regional Council Rebecca King Kelly McGourty Sound Transit Lisa Enns Jim Moore Amy Shatzkin Southwest Regional Transportation Council Bob Hart Spokane Transit Authority Karl Otterstrom Joel Soden STAR Lab Sa Xiao Washington State Transportation Center (TRAC) Mark Hallenbeck John Ishimaru Duane Wright

WSDOT Matt Beaulieu Mike Bernard Mike Bjordahl Bradley Bobbitt Daniela Bremmer Ken Burgstahler Dave Bushnell Paula Connelley Mike Clark Todd Daley Mark Eldridge Mike Ellis Vince Fairhurst Sreenath Gangula Hien Giang Manouchehr Goudarzi Matt Hanbey Monica Harwood Joe Irwin Annie Johnson Steve Kim Todd Lamphere Bill Legg Sarah Lowry Jim Mahugh Diane McGuerty Patricia Michaud Janarthanan Natarajan TJ Nedrow John Nisbet Kynan Patterson Charles Prestrud Trevor Skelton Tim Sexton Raymond Shank Joe St Charles Anna St Martin Stan Suchan Mike Villnave Alison Wallingford Pat Whittaker Anna Yamada Shuming Yan

in partnership with

2 | WSDOT 2013 Corridor Capacity Report

Executive Summary

Executive Summary

Congestion remained below pre-recession levels in 2012

Statewide congestion data for the past six years (2007 through 2012) indicate that 2009 was the least congested year for Washington drivers The statewide congestion indicators are still below pre-recession levels as the economy continues to rebound

In 2012 each person in the state was delayed in traffic for 4 hours and 30 minutes This means an average household of two commuters spent 9 extra hours of time on the road due to traffic This is 12 minutes lower than in 2010 when the per-person vehicle hours of delay on state highways was 4 hours and 42 minutes

The delay on state highways cost Washington citizens and businesses $780 million in 2012 This is roughly $115 per person For a household of two commuters this is $230 each year To put it in perspective this amount is equal to 60 gallons of gas ($384 per gallon) allowing the household to drive approximately 1500 miles at 25 miles per gallon

When miles traveled are averaged across the population it is as if each Washingtonian drove 8303 miles in 2012 of which 4578 were on the state highway system Even though this sounds like a lot the person-miles traveled in 2012 were actually lower than 2010 by 24 on all roadways and 31 on state highways

WSDOT introduces new multi-modal measures With this edition WSDOT introduces new performance measures and a new graphical display of information all with an emphasis on multi-modal and person-based metrics

The new measures include park and ride (PampR) lot utilization routinely congested highway segments greenhouse gas (GHG) emissions transit ridership and the costs of congestion for commuters

The graphical display shows key system performance information related to specific urban corridors all aligned with a map of the corridor

Park and ride lot utilization rates The PampR lot locations are presented on the map along with available spaces and percent occupied in a table to help tell the multi-modal system performance story The PampR lots primarily cater to transit services on the corridor - other PampR lots exist as well

Routinely congested highway segments For the first time WSDOT is presenting the routinely congested segments in graphical format on each of the corridors statewide (except I-90 in Spokane) The routinely congested segments are identified for morning and evening commutes by direction of travel length of congested segment in miles and duration of congestion in hours

Greenhouse gas emissions estimated for corridors The greenhouse gas emissions from vehicles on the 40 high-demand commute corridors in the central Puget Sound area totaled 12156 metric tons of carbon dioxide (CO2) each weekday in 2012 To put it in perspective this means an average commuter who drives in the central Puget Sound area is responsible for emitting more than 13 pounds of CO2 daily This estimate is for a subset of all Seattle area daily travel These emissions do not include principal arterials and surface streets in the area

Transit takes more than 43800 cars off the road daily In 2012 there were nearly 70600 daily transit riders during the peak commute periods on the high-demand corridors in the central Puget Sound area This took more than 43800 cars off the road which in turn avoided approximately 674700 pounds of CO2 emissions daily For example both buses and light rail from SeaTac to Seattle in the morning and from Seattle to SeaTac in the evening carried about 7600 and 10200 passengers each day during the peak periods respectively

Congestion costs increase on 21 corridors The cost of commute congestion (wasted time and gas) in the central Puget Sound area on the 40 high-demand commute routes increased on 21 decreased on 14 and remained the same on 5 commutes The largest reductions in commute congestion cost were on the SR 520 corridor Tolls were implemented in December 2011 and a significant number of commuters choose to drive alternate routes rather than pay the toll

For example the cost of congestion for commute trips on the I-5 corridor in 2012 for a round trip to and from work ranged from $400 to $1500 annually for each person The Everett-Seattle round trip had the highest commute congestion cost on this corridor in 2012

WSDOT 2013 Corridor Capacity Report | 3

-

Dashboard of Indicators

2013 Corridor Capacity Report Dashboard of Indicators Difference Dollar values are inflation-adjusted measured in 2012 dollars 2007 2008 2009 2010 2011 2012 lsquo10 vs lsquo12

Demographic and economic indicators

State population (thousands) 6525 6608 6672 6725 6768 6818 14

Gasoline price per gallon (annual average)1 $329 $364 $276 $317 $380 $384 208

Washington unemployment rate (annual) 46 54 94 99 92 82 -17

Washington real per person income2 $46265 $46706 $44386 $44369 $45197 $45941 35

Multi-modal performance measures

Drive alone commuting rate3 731 715 721 730 733 - -

Carpooling commuting rate3 114 122 113 105 102 - -

Public transit commuting rate3 54 55 59 55 56 - -

Transit ridership4 (in millions) 1952 2156 2101 2078 2130 - -

Washington State Ferries ridership4 (in millions) 241 233 225 226 223 - -

Bicycling and walking commuting rate3 41 45 43 44 42 - -

Statewide congestion indicators

Per person total vehicle miles traveled on all public roads state highways only

All public roads vehicle miles traveled (VMT) in billions 56964 55447 56461 57191 56965 56607 -10

All public roads per person VMT in miles 8730 8391 8462 8505 8417 8303 -24

State highways VMT in billions 31970 30742 31456 31764 31455 31214 -17

State highways per person VMT in miles 4900 4652 4714 4724 4648 4578 -31

Congestion on state highway system

Total state highway lane miles 18425 18500 18571 18630 18642 18659 02

Lane miles of state highway system congested 1032 962 966 1025 1007 1026 00

Percent of state highway system congested5 56 52 52 55 54 55 00

Per person total and cost of delay on state highways

Annual hours of per person delay on state highways6 54 53 42 47 48 45 -43

Total vehicle hours of delay in millions of hours6 351 348 281 316 325 309 -24

Cost of delay on state highways (2012 dollars)6 $931 $890 $721 $800 $821 $780 -24

Corridor specific congestion indicators (52 central Puget Sound area commutes)

Annual Maximum Throughput Travel Time Index (MT3I)7 145 1258 130 139 135 139 00

Number of commute routes with MT3I gt 17 46 418 43 45 44 44

WSDOT congestion relief projects

Number of completed Nickel and TPA mobility projects as 33 43 73 91 65 82of December 31 of each year (cumulative)

Cumulative project value (dollars in millions) $963 $1289 $2212 $2596 $2802 $3851 $1255

Data source Washington State Office of Financial Management Economic and Revenue Forecast Council Bureau of Economic Analysis US Department of Energy - Energy Information Administration Bureau of Labor Statistics ndash Consumer Price Index WSDOT State Highway Log US Census Bureau - American Community Survey National Transit Database

Notes WSDOTrsquos annual Congestion Report is renamed as the Corridor Capacity Report beginning with the 2013 publication Analysis in the 2013 Corridor Capacity Report examines 2010 and 2012 annual data 2007 is included to show pre-recession levels All dollar values are inflation-adjusted using the Consumer Price Index (CPI) 1 Gas prices are reported in 2012 dollars and represent yearly averages 2 Real per capita income is measured as total statewide personal income in 2012 dollars divided by state population 3 Based on one-year estimates from the American Community Survey commuting rates are of workers age 16 and older 4 Ridership means the number of boardings also called unlinked passenger trips 5 Based on below 70 of posted speed 6 Based on maximum throughput speed threshold (85 of posted speed) 7 MT3I greater than one means the commute route experiences congestion 8 2008 data not available for four of the 52 routes For more information see gray box in the 2009 Congestion Report p 15

4 | WSDOT 2013 Corridor Capacity Report Dashboard of Indicators

-1

18

Introduction

Introduction

WSDOTrsquos Corridor Capacity Report presents detailed analysis for current and baseline years The Corridor Capacity Reportrsquos detailed analysis shows where and how much congestion occurs and whether it has grown on state highways The report focuses on the most traveled commute routes in the urban areas of the state ie central and south Puget Sound areas Vancouver Spokane and the Tri-Cities area and elsewhere around the state where data is available WSDOT and University of Washington experts use a two-year span to more accurately identify changes and trends seen on the state highway system that may be missed by looking at a one-year comparison For the 2013 Corridor Capacity Report calendar year 2012 is the current analysis year data while 2010 data is the baseline for comparison Some exceptions were made to use 2011 data in place of 2010 due to data availability and data quality

This year WSDOT is introducing new performance metrics listed below along with the standard metrics

Key congestion performance measures

Measure Definition

WSDOTrsquos congestion measurement principles Use real-time measurements (rather than computer

models) whenever and wherever possible

Use maximum throughput as the basis for congestion measures

Distinguish between and measure both congestion due to incidents (non-recurrent) and congestion due to inadequate capacity (recurrent)

Show how reducing non-recurrent congestion from incidents will improve the travel time reliability

Demonstrate both long-term trends and short-toshyintermediate-term results

Communicate possible congestion fixes using an ldquoapples-to-applesrdquo comparison with the current situation For example ldquoIf the trip takes 20 minutes today how many minutes less will it be if WSDOT improves the interchangerdquo

Use ldquoplain Englishrdquo to describe measurements and results

NEW Commute congestion cost Cost due to wasted fuel and time associated with travel during congested conditions (speeds slower than 45 mph) that could have been spent productively elsewhere

NEW Greenhouse gas emissions The pounds of carbon dioxide (CO2) emitted during peak period commutes The per-person emissions per trip during peak periods The emissions avoided by use of transit services

NEW Transit ridership and used Ridership on buses light rail and commuter rail during the peak periods between commute route capacity origins and destinations Used capacity in percent of available seats that are used on transit already

serving commute routes

NEW Park and Ride capacity and use Number of parking spaces and percent of capacity used on an average annual weekday

NEW Routinely congested segments Sections of roadway where traffic demand reaches capacity on at least 40 of the weekdays annually

Average peak travel time The average travel time on a route during the peak five-minute interval for all weekdays of the calendar year

95th percentile reliable travel time Travel time with 95 certainty (ie on-time 19 out of 20 work days)

Maximum Throughput Travel Time Index (MTsup3I) The ratio of average peak travel time compared to maximum throughput speed travel time

Percent of days when speeds are Percent of days annually that observed speeds for one or more five-minute interval is less than 36 mph less than 36 mph (severe congestion) on key highway segments

Vehicle throughput Measures how many vehicles move through a highway segmentspot location in an hour

Lost throughput productivity Percentage of a highwayrsquos lost vehicle throughput due to congestion when compared to the maximum five-minute weekday flow rate observed at a particular location of the highway for that calendar year

Per person delay (other forms of delay The average total daily hours of delay per person based on the maximum throughput speed (85 of such as total delay) posted speed) measured annually for weekdays

Percent of the system congested Percent of total state highway lane miles that drop below 70 of the posted speed limit

Duration of congestion The time period in minutes when speeds fall below 45 mph

HOV lane reliability An HOV lane is deemed ldquoreliablerdquo as long as it maintains an average speed of 45 mph for 90 of the peak hour

Person throughput Measures how many people on average move through a highway segment during peak periods

Before and After analysis Before and After performance analysis of selected highway congestion relief projects and strategies

Average incident clearance time Operational measure defined as the time from notification of the incident until the last responder has left (Statewide) the scene for all incidents responded to by WSDOT Incident Response personnel statewide

WSDOT 2013 Corridor Capacity Report | 5

2012 greenhouse gas emissions factors for four categories of vehicles decline with increasing speed Carbon dioxide emissions in pounds of CO2 per vehicle mile traveled Speed in miles per hour

Introduction

Introduction

Measuring cost of congestion greenhouse gas emissions and transit

WSDOTrsquos new multi-modal system performance measures include commute congestion cost trip-based vehicle emissions transit usage park and ride lot capacity and use and locations that experience routine congestion

NEW WSDOT quantifies the congestion cost for individuals and commutes With the 2013 Corridor Capacity Report WSDOT is for the first time quantifying commute congestion cost at the individual commuter level to answer the question ldquohow much does congestion cost a daily commuterrdquo Commute congestion cost is based on the duration of congestion that represents the timeframe during which users can expect to travel at speeds below 45 mph (75 of posted speed) during their daily commute While daily commuters may build extra time and operating costs into their routines and budgets to account for traveling during congested periods congestion still represents costs lost opportunities and lost productivity that negatively affect individuals and society

Commute congestion cost = (Average travel time ndash Travel time at threshold speed) X Traffic volume within the duration of congestion X Cost of travel

Commute congestion cost is computed for every five-minute interval within the time that a particular commute is experiencing congestion This methodology underestimates commute congestion cost because it does not capture the periodic slowdowns (when speeds drop below 45 mph) briefly experienced during individual trips along the length of the commute Commute congestion cost can be estimated using the equation above

NEW WSDOT quantifies greenhouse gas emissions from commuters on central Puget Sound area routes WSDOTrsquos new metric captures the approximate pounds of carbon dioxide (CO2) emitted during a one-way commute trip Total emissions during the peak period are reported along with the emissions per person The per-person metric takes into consideration the average number of people in each vehicle in the single-occupancy vehicle lanes

CO2 emissions from vehicles are directly related to the speed at which the vehicle is traveling For speeds slower than 25 mph the emissions quickly escalate to more than five times as many pounds of CO2 per mile compared to at faster speeds (see example graph above right) However there is little variation in emissions per vehicle mile traveled between

Example greenhouse gas emissions factors for four categories of vehicles decline with increasing speed Carbon dioxide emissions in pounds of CO2 per vehicle mile traveled Speed in miles per hour 25

0

5

10

15

20

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75

Transit buses

Passenger car amp truck

Medium trucks

Heavy trucks

Data source Puget Sound Regional Council

Note Factors for 2012 restricted access urban roadways Emissions factors do not reflect relative emissions per person mile traveled by the different modes of transportation

35 and 65 mph the typical range of speeds on Washington highways Emissions also vary by the type of vehicles medium and large trucks emit more CO2 per mile than a typical passenger car Total emissions on a roadway during the peak period fluctuate more with the volume of vehicles on the roadway year to year than with the changes in average speed unless the average speeds are slower than 25 mph

CO2 emissions are computed for every five-minute interval within the morning or evening peak period applying emission factors based on the mix of trucks and passenger vehicles and the average speed during that time CO2

emissions can be estimated using the equation below

CO2 emissions during peak period = Sum for every 5 minutes during peak period ((Truck X Truck emission factor) + (1 - Truck) X Car emission factor) X Traffic volume within the 5-minute interval X Trip length)

Per person per trip CO2 emissions are calculated using the emissions during the peak period the average number of people in each vehicle in the single-occupancy vehicle lanes and the total traffic volume on the commute corridor during the peak period The per-person emissions can be estimated using the equation below

CO2 per person trip = (CO2 emissions during peak period) (Traffic volume during peak period X Average observed trip vehicle occupancy)

Emissions avoided by transit use are estimated with the following equation for commute trips during the peak periods

CO2 avoided = Number of transit riders during peak period X 062 SOV miles avoided per transit passenger mile X Trip length X 10 pound of CO2 per mile traveled

6 | WSDOT 2013 Corridor Capacity Report

Introduction

Introduction

WSDOTrsquos congestion measurement principles in action

NEW Quantifying the transit use along central Puget Sound area commute routes WSDOT for the first time measures system capacity across modes along the central Puget Sound area commute routes This includes the utilization of the HOV lanes compared to adjacent SOV lanes (see person-throughput analysis on p 66) and the capacity used on public transit services Sound Transit King County Metro and Community Transit provide public transportation services throughout the central Puget Sound area WSDOT aligned the bus light rail and Sounder commuter rail routes with the 40 peak period commute trips (see pp 49-52) WSDOT computed average daily transit statistics for each commute for ridership average load (percent of seats used) vehicle trips off the SOV lanes and greenhouse gas emissions avoided by transit ridership

NEW Park and ride lot use supports transit Park and ride (PampR) lots provide locations for a commuter to meet up with carpool or vanpool participants or to catch a bus to work if transit does not come close to their home WSDOT tracks the average percent of available space used PampR lots at or near capacity discourage potential transit users and ridesharers because they do not have a reliable place to park

NEW Routinely congested segments illustrate where demand exceeds capacity Specific sections of the urban highway system experience routine congestion due to constrained conditions WSDOT tracks how often demand exceeds capacity on the highway system and documents the frequency and length of time (duration) the route is congested This type of congestion is not related to incidents or collisions although such occurrences accentuate the regular congestion

NEW WSDOT expands commute trip analysis coverage around the state WSDOTrsquos 2013 Corridor Capacity Report expands the commute trip analysis coverage to include south Puget Sound and Vancouver area commute trips in addition to trips in the central Puget Sound and Spokane areas This brings the total to 82 commute trips analyzed statewide

WSDOT collects real-time traffic data WSDOT collects real-time data for all 82 commute routes in urban areas around the state including the central and south Puget Sound areas (52 and 20 routes respectively) the Vancouver area (8 routes) the Spokane area (2 routes) and on other highways statewide

In the central Puget Sound area alone data is collected from about 6800 loop detectors embedded in the pavement throughout 235 centerline miles (1300 lane miles) Similarly the south Puget Sound area has 128 active data sensors that stretch along 77 centerline miles (270 lane miles) Other urban areas of the state have loop detectors and other technologies used for traffic data collection WSDOT for the first time uses private sector speed data for Vancouver area commute trip analysis to complement the existing WSDOT data set

The data collected from these WSDOT loop detectors are quality controlled using a variety of software processes WSDOT uses this data to analyze system performance In tracking and communicating performance results WSDOT adheres to congestion measurement principles including the use of more accurate real-time data rather than modeled data and uses language and terminology that is meaningful to the public (ldquoplain Englishrdquo) See p 5 for a list of performance measures and principles

Measures that matter to drivers speed travel time and reliability Speed is a metric that carries importance not only with WSDOT but with the general public as well Measuring the time to get from point A to point B is one of the most easily understood congestion measures Travel time reliability also matters to commuters and businesses because it is important for people and goods to be on time all the time

WSDOTrsquos Corridor Capacity Report examines travel times on the 82 commute trips around the state with a particular focus on 40 high-demand routes in the central Puget Sound area Travel times for high occupancy vehicle (HOV) lanes along many of these same corridors are also reported

The metrics used in the commute trip analysis include the average peak travel time the 95th percentile reliable travel time the duration of congestion and the percent of weekdays when average travel speeds are below 36 mph The performance of an individual route compares data with the current analysis year to the baseline year

WSDOTrsquos previously published person-based measures (per capita for statewide measures) include per person vehicle miles traveled and per person hours of delay in traffic (statewide urban area and corridor based) along with the per person trip travel time on commute corridors

WSDOT expanded reliability analysis looks at a range

WSDOT 2013 Corridor Capacity Report | 7

Introduction

Introduction

How do WSDOTrsquos congestion performance measures work

of travel time percentiles in the 2009 Congestion Report This analysis allows WSDOT to examine travel time changes at a finer level of detail and better evaluate its operational strategies

Real-time travel times for key commute routes in central and south Puget Sound areas Spokane and Vancouver are available to the public and updated every 5 minutes on the WSDOT website at www wsdotwagovtrafficseattletraveltimes

Measuring vehicle miles traveled (VMT) WSDOT examines vehicle miles traveled (VMT) as a volume metric for each commute route VMT is calculated for peak hours for the commute routes and all-day VMT is reported as part of the statewide metric WSDOT examines factors such as the use of public transportation population change unemployment rates real personal income and fuel prices as they relate to volume and travel time changes

VMT allows WSDOT to quantify travel along a route Because traffic volumes vary along a route each locationrsquos traffic volume is multiplied by the representative length of the route and these values are added up to obtain a routersquos total VMT WSDOT uses this measure to better understand the number of trips taken on certain commute routes and the total miles traveled on state highways This helps WSDOT predict future demand and establish improvement needs

Traffic volume is a vehicle count at a given roadway location It is measured by a detector in each lane at the location WSDOT has loop detectors spaced at roughly half-mile intervals throughout the central Puget Sound area freeway network and at various locations on the highway system statewide

WSDOT uses maximum throughput to measure congestion performance To operate the highway system as efficiently as possible the speed at which the highest number of vehicles can move through a highway segment (maximum throughput) is more meaningful than posted speed as the basis of measurement WSDOT aims to provide and maintain a system that yields the most productivity and efficiency rather than a system that is free flowing but where fewer vehicles can pass through a segment during peak travel periods

Understanding maximum throughput An adaptation of the Understanding maximum throughput An adaptation speedvolume curve of the speedvolume curveMay 2010 weekday volume 6-10 am I-405 NB at 24th NE I-405 northbound at 24th NE 6-10 am weekdays volume in May 2010Speed limit 60 mph Maximum throughput speed ranges between Speed limit 60 mph Maximum throughput speed ranges between70 and 85 of posted speed 70-85 of posted speed

When few vehicles use a70 mph highway they can all travel

0 mph

10 mph

20 mph

30 mph

40 mph

50 mph

60 mph near the speed limit

Maximum throughput

As still more vehicles use a highway all traffic slows and capacitydecreases

If more vehicles use a highway traffic slows but capacity remains high

If too many vehicles usea highway congestion greatly reduces capacity

0 500 1000 1500 2000 2500 Volume of vehicles per hour per lane

Data source WSDOT Northwest Region Traffic Office

Maximum throughput is achieved when vehicles travel at speeds between 42 and 51 mph (roughly 70 to 85 of a posted 60 mph speed) At maximum throughput speeds highways are operating at peak efficiency because more vehicles are passing through the segment than at posted speeds This happens because drivers at maximum throughput speeds can safely travel with a shorter distance between vehicles than they can at posted speeds

Maximum throughput speeds vary from one highway segment to the next depending on prevailing roadway design (roadway alignment lane width slope shoulder width pavement conditions presence or absence of median barriers) and traffic conditions (traffic composition conflicting traffic movements heavy truck traffic etc) The maximum throughput speed is not static and can change over time as conditions change Ideally maximum throughput speeds for each highway segment should be determined through comprehensive traffic studies and validated by field surveys For surface arterials (interrupted flow facilities) maximum throughput speeds are difficult to predict because they are influenced by interruptions in flow due to the conflicting traffic movements at intersections

WSDOT uses the maximum throughput standard as a basis for measurement to assess travel delay relative to a highwayrsquos most efficient condition at maximum throughput speeds (85 of posted speed) For more information on changes in travel delay performance please see pp 42-64

8 | WSDOT 2013 Corridor Capacity Report

Introduction

Introduction

WSDOT thresholds for system efficiency maximum throughput

WSDOT also uses maximum throughput as a basis for evaluating the system through the following measures

Total delay and per person delay

Percent of the system that is delayed and congested

Lost throughput productivity

Maximum Throughput Travel Time IndexmdashMT3I (for a more detailed discussion see p 46)

Duration of the congested period

Commute congestion cost

Measuring per person delay and total delay Delay can be measured at various speed thresholds such as free flow speed posted speed or maximum throughput speeds WSDOT uses maximum throughput speeds rather than free flow or posted speeds to measure delay relative to the highwayrsquos most efficient operating condition WSDOT measures travel delay statewide and on five major commute corridors in the central Puget Sound area In addition to measuring total hours of delay WSDOT also evaluates annual per person delay and the cost of delay to drivers and businesses

Measuring the percentage of the highway system that is delayed This measure allows WSDOT to assess the percentage of its system that is operating below maximum throughput speed creating delay for the traveling public The metric is

calculated for an average weekday by dividing the number of lane miles where speeds drop below 85 of posted speeds by total lane miles It allows differentiation between delayed lane miles in urban and rural areas of the state

Measuring the percentage of the highway system that is congested This measure allows WSDOT to evaluate what percentage of the system that the agency manages is congested It is calculated for an annual average weekday by dividing the number of lane miles where speeds drop below 70 of posted speeds by total lane miles This measure also differentiates between the portion of congested lane miles in urban versus rural areas of the state

Evaluating vehicle throughput productivity Highways are engineered to move specific volumes of vehicles based on the number of lanes and other design aspects Highways are not necessarily operating at their maximum efficiency when all vehicles are moving at 60 mph (the typical urban highway posted speed limit in Washington) As congestion increases speeds decrease and fewer vehicles pass through the corridor Throughput productivity may decline from a maximum of about 2000 vehicles per hour per lane traveling at speeds between 42 and 51 mph (100 efficiency) to as low as 700 vehicles per hour per lane (35 efficiency) at speeds less than 30 mph

WSDOT state highway speed thresholds for congestion measurement

Measure Threshold Description

Posted speed 60 mph Vehicles are moving through a highway segment at the posted speed but to travel safely at higher speeds and allow sufficient stopping distance drivers must maintain more space between vehicles Fewer vehicles can pass through the segment in a given amount of time and the segment is not operating at maximum efficiency

Maximum throughput speed (optimal flow speed)

70-85 of posted speed (about 42-51 mph)

Vehicles are moving slower than the posted speed and the number of vehicles moving through the highway segment is higher These speed conditions enable the segment to reach its maximum productivity in terms of vehicle volume and throughput (based on the speedvolume curve) This threshold range is used for highway system deficiency analysis

Duration of congested period (urban commute routes)

Duration of time vehicle speeds drop below 75 of posted speeds (45 mph)

The average weekday peak time period (in minutes) when average vehicle speeds drop below 75 of posted speeds (about 45 mph) Drivers have less than optimal spacing between cars and the number of vehicles that can move through a highway segment is reduced The highway begins to operate less efficiently under these conditions than at maximum throughput

Percent of state highway system delayed

Less than 85 of posted speeds

Percent of total state highway lane miles that drop below 85 of the posted speed limit

Percent of state highway system congested

Less than 70 of posted speeds

Percent of total state highway lane miles that drop below 70 of the posted speed limit

Severe congestion

Less than 60 of posted speed (less than 36 mph)

Speeds and spacing between vehicles continue to decline on a highway segment and highway efficiency operates well below maximum productivity

WSDOT 2013 Corridor Capacity Report | 9

Introduction

Introduction

Measuring per person delay vehicle throughput reliability

Measuring travel time reliability WSDOT uses the 95th percentile reliable travel time as its key reliability metric for the 82 commute trips monitored statewide Travel time reliability is measured in percentiles For example 95th percentile travel times track the amount of time a traveler will need to plan in order to be on time 95 of the time (19 of 20 weekday trips) 80th percentile travel times will ensure the traveler is on time four out of five weekday trips A benefit to using percentile measures is they are not affected by outlier values generally the longest travel times Using a range of percentiles ndash from the 50th (median) to the 95th ndash allows WSDOT to track changes in reliable travel times over the years at a finer level in order to evaluate operational improvements more accurately Changes in the 80th and 90th percentiles are likely to represent travel times that are the result of routine incidents and other factors that the agency can influence with

5

5

90 405

167

512

3

305

104

16

520

522

9

203

202

2

2

18

525

Seattle Bellevue

Everett

Tacoma

Renton

Kent

Auburn

Puyallup

Lakewood

Federal Way

Mukilteo

Poulsbo

Bremerton

Purdy

Fife

Redmond

509

Pierce County

Pierce County Kitsap County

King County

King County

Snohomish County

Kitsap Peninsula

Vashon Island

BainbridgeIsland

PugetSound

Lake Washington

WhidbeyIsland

Sea-Tac Intrsquol Airport

Tacoma Narrows Bridge

167

Snoh

omish

County

Island

County

5

104

3

Freeway HOV amp HOT Lane System

HOV lanes operate 24 hours HOV lanes operate 24 hours 3+ HOV lanes operate 5 am - 7 pm HOV lanes in Reversible Express Lane Roadway (variable hours) HOT lanes operate 5 am - 7 pm Construction funded Construction unfunded or partially funded Direct Access Ramps ndash Open Direct Access Ramps ndash Open(Transit Only) Direct Access Ramps ndash Future

NOTE HOV lanes require two or morepeople (2+) unless otherwise notedHours of operation are for all seven daysof the week

T

T

Freeway HOV and HOT lane systems in the greater Puget Sound area

10 | WSDOT 2013 Corridor Capacity Report

operational strategies See pp 46-48 for detailed reliability data and pp 78-84 for more on operational strategies such as tolling Active Traffic Management Intelligent Transportation Systems (ITS) and Incident Response

WSDOT examines high occupancy vehicle (HOV) trip performance WSDOT uses several measures to evaluate HOV trip performance WSDOT and the Puget Sound Regional Council (PSRC) adopted a reliability standard for HOV lanes which states that for 90 of the peak hour HOV lanes should maintain an average speed of 45 mph This is the basis for WSDOTrsquos HOV reliability measure WSDOT also measures person throughput to gauge the effectiveness of HOV lanes in carrying more people compared to single occupancy vehicle (SOV) lanes and reports HOV trip travel times compared to SOV trip travel times

The map at left depicts the HOV and HOT lane system in the Puget Sound area About 310 lane-miles of the planned 320-mile Puget Sound area HOV network have been completed More information about the HOV lane network can be found starting on p 65 or at httpwwwwsdotwagovhov

Using Before and After analyses to review project performance As of June 30 2013 WSDOT completed 344 out of 421 projects funded by the 2003 and 2005 gas tax packages of which 91 were congestion relief projects To measure how well these investments are mitigating congestion WSDOT has implemented Before and After project studies to analyze impacts on travel times and delay On highway segments without in-pavement loop detectors data is collected using automated license plate recognition (ALPR) cameras blue tooth readers or moving test vehicles Before and After performance evaluations are performed on key congestion relief projects to evaluate the benefits of projects that improve system efficiency See pp 85-90

Quantifying Incident Response benefits WSDOT uses several measures to evaluate the performance of its Incident Response (IR) program Beginning in the 2011 Congestion Report WSDOT quantifies the annual economic benefits provided by the IR program For details on the IR program and how it helps alleviate non-recurrent congestion see pp 81-84

Executive Summary

Executive Summary

Congestion remained below pre-recession levels in 2012

Statewide congestion data for the past six years (2007 through 2012) indicate that 2009 was the least congested year for Washington drivers The statewide congestion indicators are still below pre-recession levels as the economy continues to rebound

In 2012 each person in the state was delayed in traffic for 4 hours and 30 minutes This means an average household of two commuters spent 9 extra hours of time on the road due to traffic This is 12 minutes lower than in 2010 when the per-person vehicle hours of delay on state highways was 4 hours and 42 minutes

The delay on state highways cost Washington citizens and businesses $780 million in 2012 This is roughly $115 per person For a household of two commuters this is $230 each year To put it in perspective this amount is equal to 60 gallons of gas ($384 per gallon) allowing the household to drive approximately 1500 miles at 25 miles per gallon

When miles traveled are averaged across the population it is as if each Washingtonian drove 8303 miles in 2012 of which 4578 were on the state highway system Even though this sounds like a lot the person-miles traveled in 2012 were actually lower than 2010 by 24 on all roadways and 31 on state highways

WSDOT introduces new multi-modal measures With this edition WSDOT introduces new performance measures and a new graphical display of information all with an emphasis on multi-modal and person-based metrics

The new measures include park and ride (PampR) lot utilization routinely congested highway segments greenhouse gas (GHG) emissions transit ridership and the costs of congestion for commuters

The graphical display shows key system performance information related to specific urban corridors all aligned with a map of the corridor

Park and ride lot utilization rates The PampR lot locations are presented on the map along with available spaces and percent occupied in a table to help tell the multi-modal system performance story The PampR lots primarily cater to transit services on the corridor - other PampR lots exist as well

Routinely congested highway segments For the first time WSDOT is presenting the routinely congested segments in graphical format on each of the corridors statewide (except I-90 in Spokane) The routinely congested segments are identified for morning and evening commutes by direction of travel length of congested segment in miles and duration of congestion in hours

Greenhouse gas emissions estimated for corridors The greenhouse gas emissions from vehicles on the 40 high-demand commute corridors in the central Puget Sound area totaled 12156 metric tons of carbon dioxide (CO2) each weekday in 2012 To put it in perspective this means an average commuter who drives in the central Puget Sound area is responsible for emitting more than 13 pounds of CO2 daily This estimate is for a subset of all Seattle area daily travel These emissions do not include principal arterials and surface streets in the area

Transit takes more than 43800 cars off the road daily In 2012 there were nearly 70600 daily transit riders during the peak commute periods on the high-demand corridors in the central Puget Sound area This took more than 43800 cars off the road which in turn avoided approximately 674700 pounds of CO2 emissions daily For example both buses and light rail from SeaTac to Seattle in the morning and from Seattle to SeaTac in the evening carried about 7600 and 10200 passengers each day during the peak periods respectively

Congestion costs increase on 21 corridors The cost of commute congestion (wasted time and gas) in the central Puget Sound area on the 40 high-demand commute routes increased on 21 decreased on 14 and remained the same on 5 commutes The largest reductions in commute congestion cost were on the SR 520 corridor Tolls were implemented in December 2011 and a significant number of commuters choose to drive alternate routes rather than pay the toll

For example the cost of congestion for commute trips on the I-5 corridor in 2012 for a round trip to and from work ranged from $400 to $1500 annually for each person The Everett-Seattle round trip had the highest commute congestion cost on this corridor in 2012

WSDOT 2013 Corridor Capacity Report | 3

-

Dashboard of Indicators

2013 Corridor Capacity Report Dashboard of Indicators Difference Dollar values are inflation-adjusted measured in 2012 dollars 2007 2008 2009 2010 2011 2012 lsquo10 vs lsquo12

Demographic and economic indicators

State population (thousands) 6525 6608 6672 6725 6768 6818 14

Gasoline price per gallon (annual average)1 $329 $364 $276 $317 $380 $384 208

Washington unemployment rate (annual) 46 54 94 99 92 82 -17

Washington real per person income2 $46265 $46706 $44386 $44369 $45197 $45941 35

Multi-modal performance measures

Drive alone commuting rate3 731 715 721 730 733 - -

Carpooling commuting rate3 114 122 113 105 102 - -

Public transit commuting rate3 54 55 59 55 56 - -

Transit ridership4 (in millions) 1952 2156 2101 2078 2130 - -

Washington State Ferries ridership4 (in millions) 241 233 225 226 223 - -

Bicycling and walking commuting rate3 41 45 43 44 42 - -

Statewide congestion indicators

Per person total vehicle miles traveled on all public roads state highways only

All public roads vehicle miles traveled (VMT) in billions 56964 55447 56461 57191 56965 56607 -10

All public roads per person VMT in miles 8730 8391 8462 8505 8417 8303 -24

State highways VMT in billions 31970 30742 31456 31764 31455 31214 -17

State highways per person VMT in miles 4900 4652 4714 4724 4648 4578 -31

Congestion on state highway system

Total state highway lane miles 18425 18500 18571 18630 18642 18659 02

Lane miles of state highway system congested 1032 962 966 1025 1007 1026 00

Percent of state highway system congested5 56 52 52 55 54 55 00

Per person total and cost of delay on state highways

Annual hours of per person delay on state highways6 54 53 42 47 48 45 -43

Total vehicle hours of delay in millions of hours6 351 348 281 316 325 309 -24

Cost of delay on state highways (2012 dollars)6 $931 $890 $721 $800 $821 $780 -24

Corridor specific congestion indicators (52 central Puget Sound area commutes)

Annual Maximum Throughput Travel Time Index (MT3I)7 145 1258 130 139 135 139 00

Number of commute routes with MT3I gt 17 46 418 43 45 44 44

WSDOT congestion relief projects

Number of completed Nickel and TPA mobility projects as 33 43 73 91 65 82of December 31 of each year (cumulative)

Cumulative project value (dollars in millions) $963 $1289 $2212 $2596 $2802 $3851 $1255

Data source Washington State Office of Financial Management Economic and Revenue Forecast Council Bureau of Economic Analysis US Department of Energy - Energy Information Administration Bureau of Labor Statistics ndash Consumer Price Index WSDOT State Highway Log US Census Bureau - American Community Survey National Transit Database

Notes WSDOTrsquos annual Congestion Report is renamed as the Corridor Capacity Report beginning with the 2013 publication Analysis in the 2013 Corridor Capacity Report examines 2010 and 2012 annual data 2007 is included to show pre-recession levels All dollar values are inflation-adjusted using the Consumer Price Index (CPI) 1 Gas prices are reported in 2012 dollars and represent yearly averages 2 Real per capita income is measured as total statewide personal income in 2012 dollars divided by state population 3 Based on one-year estimates from the American Community Survey commuting rates are of workers age 16 and older 4 Ridership means the number of boardings also called unlinked passenger trips 5 Based on below 70 of posted speed 6 Based on maximum throughput speed threshold (85 of posted speed) 7 MT3I greater than one means the commute route experiences congestion 8 2008 data not available for four of the 52 routes For more information see gray box in the 2009 Congestion Report p 15

4 | WSDOT 2013 Corridor Capacity Report Dashboard of Indicators

-1

18

Introduction

Introduction

WSDOTrsquos Corridor Capacity Report presents detailed analysis for current and baseline years The Corridor Capacity Reportrsquos detailed analysis shows where and how much congestion occurs and whether it has grown on state highways The report focuses on the most traveled commute routes in the urban areas of the state ie central and south Puget Sound areas Vancouver Spokane and the Tri-Cities area and elsewhere around the state where data is available WSDOT and University of Washington experts use a two-year span to more accurately identify changes and trends seen on the state highway system that may be missed by looking at a one-year comparison For the 2013 Corridor Capacity Report calendar year 2012 is the current analysis year data while 2010 data is the baseline for comparison Some exceptions were made to use 2011 data in place of 2010 due to data availability and data quality

This year WSDOT is introducing new performance metrics listed below along with the standard metrics

Key congestion performance measures

Measure Definition

WSDOTrsquos congestion measurement principles Use real-time measurements (rather than computer

models) whenever and wherever possible

Use maximum throughput as the basis for congestion measures

Distinguish between and measure both congestion due to incidents (non-recurrent) and congestion due to inadequate capacity (recurrent)

Show how reducing non-recurrent congestion from incidents will improve the travel time reliability

Demonstrate both long-term trends and short-toshyintermediate-term results

Communicate possible congestion fixes using an ldquoapples-to-applesrdquo comparison with the current situation For example ldquoIf the trip takes 20 minutes today how many minutes less will it be if WSDOT improves the interchangerdquo

Use ldquoplain Englishrdquo to describe measurements and results

NEW Commute congestion cost Cost due to wasted fuel and time associated with travel during congested conditions (speeds slower than 45 mph) that could have been spent productively elsewhere

NEW Greenhouse gas emissions The pounds of carbon dioxide (CO2) emitted during peak period commutes The per-person emissions per trip during peak periods The emissions avoided by use of transit services

NEW Transit ridership and used Ridership on buses light rail and commuter rail during the peak periods between commute route capacity origins and destinations Used capacity in percent of available seats that are used on transit already

serving commute routes

NEW Park and Ride capacity and use Number of parking spaces and percent of capacity used on an average annual weekday

NEW Routinely congested segments Sections of roadway where traffic demand reaches capacity on at least 40 of the weekdays annually

Average peak travel time The average travel time on a route during the peak five-minute interval for all weekdays of the calendar year

95th percentile reliable travel time Travel time with 95 certainty (ie on-time 19 out of 20 work days)

Maximum Throughput Travel Time Index (MTsup3I) The ratio of average peak travel time compared to maximum throughput speed travel time

Percent of days when speeds are Percent of days annually that observed speeds for one or more five-minute interval is less than 36 mph less than 36 mph (severe congestion) on key highway segments

Vehicle throughput Measures how many vehicles move through a highway segmentspot location in an hour

Lost throughput productivity Percentage of a highwayrsquos lost vehicle throughput due to congestion when compared to the maximum five-minute weekday flow rate observed at a particular location of the highway for that calendar year

Per person delay (other forms of delay The average total daily hours of delay per person based on the maximum throughput speed (85 of such as total delay) posted speed) measured annually for weekdays

Percent of the system congested Percent of total state highway lane miles that drop below 70 of the posted speed limit

Duration of congestion The time period in minutes when speeds fall below 45 mph

HOV lane reliability An HOV lane is deemed ldquoreliablerdquo as long as it maintains an average speed of 45 mph for 90 of the peak hour

Person throughput Measures how many people on average move through a highway segment during peak periods

Before and After analysis Before and After performance analysis of selected highway congestion relief projects and strategies

Average incident clearance time Operational measure defined as the time from notification of the incident until the last responder has left (Statewide) the scene for all incidents responded to by WSDOT Incident Response personnel statewide

WSDOT 2013 Corridor Capacity Report | 5

2012 greenhouse gas emissions factors for four categories of vehicles decline with increasing speed Carbon dioxide emissions in pounds of CO2 per vehicle mile traveled Speed in miles per hour

Introduction

Introduction

Measuring cost of congestion greenhouse gas emissions and transit

WSDOTrsquos new multi-modal system performance measures include commute congestion cost trip-based vehicle emissions transit usage park and ride lot capacity and use and locations that experience routine congestion

NEW WSDOT quantifies the congestion cost for individuals and commutes With the 2013 Corridor Capacity Report WSDOT is for the first time quantifying commute congestion cost at the individual commuter level to answer the question ldquohow much does congestion cost a daily commuterrdquo Commute congestion cost is based on the duration of congestion that represents the timeframe during which users can expect to travel at speeds below 45 mph (75 of posted speed) during their daily commute While daily commuters may build extra time and operating costs into their routines and budgets to account for traveling during congested periods congestion still represents costs lost opportunities and lost productivity that negatively affect individuals and society

Commute congestion cost = (Average travel time ndash Travel time at threshold speed) X Traffic volume within the duration of congestion X Cost of travel

Commute congestion cost is computed for every five-minute interval within the time that a particular commute is experiencing congestion This methodology underestimates commute congestion cost because it does not capture the periodic slowdowns (when speeds drop below 45 mph) briefly experienced during individual trips along the length of the commute Commute congestion cost can be estimated using the equation above

NEW WSDOT quantifies greenhouse gas emissions from commuters on central Puget Sound area routes WSDOTrsquos new metric captures the approximate pounds of carbon dioxide (CO2) emitted during a one-way commute trip Total emissions during the peak period are reported along with the emissions per person The per-person metric takes into consideration the average number of people in each vehicle in the single-occupancy vehicle lanes

CO2 emissions from vehicles are directly related to the speed at which the vehicle is traveling For speeds slower than 25 mph the emissions quickly escalate to more than five times as many pounds of CO2 per mile compared to at faster speeds (see example graph above right) However there is little variation in emissions per vehicle mile traveled between

Example greenhouse gas emissions factors for four categories of vehicles decline with increasing speed Carbon dioxide emissions in pounds of CO2 per vehicle mile traveled Speed in miles per hour 25

0

5

10

15

20

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75

Transit buses

Passenger car amp truck

Medium trucks

Heavy trucks

Data source Puget Sound Regional Council

Note Factors for 2012 restricted access urban roadways Emissions factors do not reflect relative emissions per person mile traveled by the different modes of transportation

35 and 65 mph the typical range of speeds on Washington highways Emissions also vary by the type of vehicles medium and large trucks emit more CO2 per mile than a typical passenger car Total emissions on a roadway during the peak period fluctuate more with the volume of vehicles on the roadway year to year than with the changes in average speed unless the average speeds are slower than 25 mph

CO2 emissions are computed for every five-minute interval within the morning or evening peak period applying emission factors based on the mix of trucks and passenger vehicles and the average speed during that time CO2

emissions can be estimated using the equation below

CO2 emissions during peak period = Sum for every 5 minutes during peak period ((Truck X Truck emission factor) + (1 - Truck) X Car emission factor) X Traffic volume within the 5-minute interval X Trip length)

Per person per trip CO2 emissions are calculated using the emissions during the peak period the average number of people in each vehicle in the single-occupancy vehicle lanes and the total traffic volume on the commute corridor during the peak period The per-person emissions can be estimated using the equation below

CO2 per person trip = (CO2 emissions during peak period) (Traffic volume during peak period X Average observed trip vehicle occupancy)

Emissions avoided by transit use are estimated with the following equation for commute trips during the peak periods

CO2 avoided = Number of transit riders during peak period X 062 SOV miles avoided per transit passenger mile X Trip length X 10 pound of CO2 per mile traveled

6 | WSDOT 2013 Corridor Capacity Report

Introduction

Introduction

WSDOTrsquos congestion measurement principles in action

NEW Quantifying the transit use along central Puget Sound area commute routes WSDOT for the first time measures system capacity across modes along the central Puget Sound area commute routes This includes the utilization of the HOV lanes compared to adjacent SOV lanes (see person-throughput analysis on p 66) and the capacity used on public transit services Sound Transit King County Metro and Community Transit provide public transportation services throughout the central Puget Sound area WSDOT aligned the bus light rail and Sounder commuter rail routes with the 40 peak period commute trips (see pp 49-52) WSDOT computed average daily transit statistics for each commute for ridership average load (percent of seats used) vehicle trips off the SOV lanes and greenhouse gas emissions avoided by transit ridership

NEW Park and ride lot use supports transit Park and ride (PampR) lots provide locations for a commuter to meet up with carpool or vanpool participants or to catch a bus to work if transit does not come close to their home WSDOT tracks the average percent of available space used PampR lots at or near capacity discourage potential transit users and ridesharers because they do not have a reliable place to park

NEW Routinely congested segments illustrate where demand exceeds capacity Specific sections of the urban highway system experience routine congestion due to constrained conditions WSDOT tracks how often demand exceeds capacity on the highway system and documents the frequency and length of time (duration) the route is congested This type of congestion is not related to incidents or collisions although such occurrences accentuate the regular congestion

NEW WSDOT expands commute trip analysis coverage around the state WSDOTrsquos 2013 Corridor Capacity Report expands the commute trip analysis coverage to include south Puget Sound and Vancouver area commute trips in addition to trips in the central Puget Sound and Spokane areas This brings the total to 82 commute trips analyzed statewide

WSDOT collects real-time traffic data WSDOT collects real-time data for all 82 commute routes in urban areas around the state including the central and south Puget Sound areas (52 and 20 routes respectively) the Vancouver area (8 routes) the Spokane area (2 routes) and on other highways statewide

In the central Puget Sound area alone data is collected from about 6800 loop detectors embedded in the pavement throughout 235 centerline miles (1300 lane miles) Similarly the south Puget Sound area has 128 active data sensors that stretch along 77 centerline miles (270 lane miles) Other urban areas of the state have loop detectors and other technologies used for traffic data collection WSDOT for the first time uses private sector speed data for Vancouver area commute trip analysis to complement the existing WSDOT data set

The data collected from these WSDOT loop detectors are quality controlled using a variety of software processes WSDOT uses this data to analyze system performance In tracking and communicating performance results WSDOT adheres to congestion measurement principles including the use of more accurate real-time data rather than modeled data and uses language and terminology that is meaningful to the public (ldquoplain Englishrdquo) See p 5 for a list of performance measures and principles

Measures that matter to drivers speed travel time and reliability Speed is a metric that carries importance not only with WSDOT but with the general public as well Measuring the time to get from point A to point B is one of the most easily understood congestion measures Travel time reliability also matters to commuters and businesses because it is important for people and goods to be on time all the time

WSDOTrsquos Corridor Capacity Report examines travel times on the 82 commute trips around the state with a particular focus on 40 high-demand routes in the central Puget Sound area Travel times for high occupancy vehicle (HOV) lanes along many of these same corridors are also reported

The metrics used in the commute trip analysis include the average peak travel time the 95th percentile reliable travel time the duration of congestion and the percent of weekdays when average travel speeds are below 36 mph The performance of an individual route compares data with the current analysis year to the baseline year

WSDOTrsquos previously published person-based measures (per capita for statewide measures) include per person vehicle miles traveled and per person hours of delay in traffic (statewide urban area and corridor based) along with the per person trip travel time on commute corridors

WSDOT expanded reliability analysis looks at a range

WSDOT 2013 Corridor Capacity Report | 7

Introduction

Introduction

How do WSDOTrsquos congestion performance measures work

of travel time percentiles in the 2009 Congestion Report This analysis allows WSDOT to examine travel time changes at a finer level of detail and better evaluate its operational strategies

Real-time travel times for key commute routes in central and south Puget Sound areas Spokane and Vancouver are available to the public and updated every 5 minutes on the WSDOT website at www wsdotwagovtrafficseattletraveltimes

Measuring vehicle miles traveled (VMT) WSDOT examines vehicle miles traveled (VMT) as a volume metric for each commute route VMT is calculated for peak hours for the commute routes and all-day VMT is reported as part of the statewide metric WSDOT examines factors such as the use of public transportation population change unemployment rates real personal income and fuel prices as they relate to volume and travel time changes

VMT allows WSDOT to quantify travel along a route Because traffic volumes vary along a route each locationrsquos traffic volume is multiplied by the representative length of the route and these values are added up to obtain a routersquos total VMT WSDOT uses this measure to better understand the number of trips taken on certain commute routes and the total miles traveled on state highways This helps WSDOT predict future demand and establish improvement needs

Traffic volume is a vehicle count at a given roadway location It is measured by a detector in each lane at the location WSDOT has loop detectors spaced at roughly half-mile intervals throughout the central Puget Sound area freeway network and at various locations on the highway system statewide

WSDOT uses maximum throughput to measure congestion performance To operate the highway system as efficiently as possible the speed at which the highest number of vehicles can move through a highway segment (maximum throughput) is more meaningful than posted speed as the basis of measurement WSDOT aims to provide and maintain a system that yields the most productivity and efficiency rather than a system that is free flowing but where fewer vehicles can pass through a segment during peak travel periods

Understanding maximum throughput An adaptation of the Understanding maximum throughput An adaptation speedvolume curve of the speedvolume curveMay 2010 weekday volume 6-10 am I-405 NB at 24th NE I-405 northbound at 24th NE 6-10 am weekdays volume in May 2010Speed limit 60 mph Maximum throughput speed ranges between Speed limit 60 mph Maximum throughput speed ranges between70 and 85 of posted speed 70-85 of posted speed

When few vehicles use a70 mph highway they can all travel

0 mph

10 mph

20 mph

30 mph

40 mph

50 mph

60 mph near the speed limit

Maximum throughput

As still more vehicles use a highway all traffic slows and capacitydecreases

If more vehicles use a highway traffic slows but capacity remains high

If too many vehicles usea highway congestion greatly reduces capacity

0 500 1000 1500 2000 2500 Volume of vehicles per hour per lane

Data source WSDOT Northwest Region Traffic Office

Maximum throughput is achieved when vehicles travel at speeds between 42 and 51 mph (roughly 70 to 85 of a posted 60 mph speed) At maximum throughput speeds highways are operating at peak efficiency because more vehicles are passing through the segment than at posted speeds This happens because drivers at maximum throughput speeds can safely travel with a shorter distance between vehicles than they can at posted speeds

Maximum throughput speeds vary from one highway segment to the next depending on prevailing roadway design (roadway alignment lane width slope shoulder width pavement conditions presence or absence of median barriers) and traffic conditions (traffic composition conflicting traffic movements heavy truck traffic etc) The maximum throughput speed is not static and can change over time as conditions change Ideally maximum throughput speeds for each highway segment should be determined through comprehensive traffic studies and validated by field surveys For surface arterials (interrupted flow facilities) maximum throughput speeds are difficult to predict because they are influenced by interruptions in flow due to the conflicting traffic movements at intersections

WSDOT uses the maximum throughput standard as a basis for measurement to assess travel delay relative to a highwayrsquos most efficient condition at maximum throughput speeds (85 of posted speed) For more information on changes in travel delay performance please see pp 42-64

8 | WSDOT 2013 Corridor Capacity Report

Introduction

Introduction

WSDOT thresholds for system efficiency maximum throughput

WSDOT also uses maximum throughput as a basis for evaluating the system through the following measures

Total delay and per person delay

Percent of the system that is delayed and congested

Lost throughput productivity

Maximum Throughput Travel Time IndexmdashMT3I (for a more detailed discussion see p 46)

Duration of the congested period

Commute congestion cost

Measuring per person delay and total delay Delay can be measured at various speed thresholds such as free flow speed posted speed or maximum throughput speeds WSDOT uses maximum throughput speeds rather than free flow or posted speeds to measure delay relative to the highwayrsquos most efficient operating condition WSDOT measures travel delay statewide and on five major commute corridors in the central Puget Sound area In addition to measuring total hours of delay WSDOT also evaluates annual per person delay and the cost of delay to drivers and businesses

Measuring the percentage of the highway system that is delayed This measure allows WSDOT to assess the percentage of its system that is operating below maximum throughput speed creating delay for the traveling public The metric is

calculated for an average weekday by dividing the number of lane miles where speeds drop below 85 of posted speeds by total lane miles It allows differentiation between delayed lane miles in urban and rural areas of the state

Measuring the percentage of the highway system that is congested This measure allows WSDOT to evaluate what percentage of the system that the agency manages is congested It is calculated for an annual average weekday by dividing the number of lane miles where speeds drop below 70 of posted speeds by total lane miles This measure also differentiates between the portion of congested lane miles in urban versus rural areas of the state

Evaluating vehicle throughput productivity Highways are engineered to move specific volumes of vehicles based on the number of lanes and other design aspects Highways are not necessarily operating at their maximum efficiency when all vehicles are moving at 60 mph (the typical urban highway posted speed limit in Washington) As congestion increases speeds decrease and fewer vehicles pass through the corridor Throughput productivity may decline from a maximum of about 2000 vehicles per hour per lane traveling at speeds between 42 and 51 mph (100 efficiency) to as low as 700 vehicles per hour per lane (35 efficiency) at speeds less than 30 mph

WSDOT state highway speed thresholds for congestion measurement

Measure Threshold Description

Posted speed 60 mph Vehicles are moving through a highway segment at the posted speed but to travel safely at higher speeds and allow sufficient stopping distance drivers must maintain more space between vehicles Fewer vehicles can pass through the segment in a given amount of time and the segment is not operating at maximum efficiency

Maximum throughput speed (optimal flow speed)

70-85 of posted speed (about 42-51 mph)

Vehicles are moving slower than the posted speed and the number of vehicles moving through the highway segment is higher These speed conditions enable the segment to reach its maximum productivity in terms of vehicle volume and throughput (based on the speedvolume curve) This threshold range is used for highway system deficiency analysis

Duration of congested period (urban commute routes)

Duration of time vehicle speeds drop below 75 of posted speeds (45 mph)

The average weekday peak time period (in minutes) when average vehicle speeds drop below 75 of posted speeds (about 45 mph) Drivers have less than optimal spacing between cars and the number of vehicles that can move through a highway segment is reduced The highway begins to operate less efficiently under these conditions than at maximum throughput

Percent of state highway system delayed

Less than 85 of posted speeds

Percent of total state highway lane miles that drop below 85 of the posted speed limit

Percent of state highway system congested

Less than 70 of posted speeds

Percent of total state highway lane miles that drop below 70 of the posted speed limit

Severe congestion

Less than 60 of posted speed (less than 36 mph)

Speeds and spacing between vehicles continue to decline on a highway segment and highway efficiency operates well below maximum productivity

WSDOT 2013 Corridor Capacity Report | 9

Introduction

Introduction

Measuring per person delay vehicle throughput reliability

Measuring travel time reliability WSDOT uses the 95th percentile reliable travel time as its key reliability metric for the 82 commute trips monitored statewide Travel time reliability is measured in percentiles For example 95th percentile travel times track the amount of time a traveler will need to plan in order to be on time 95 of the time (19 of 20 weekday trips) 80th percentile travel times will ensure the traveler is on time four out of five weekday trips A benefit to using percentile measures is they are not affected by outlier values generally the longest travel times Using a range of percentiles ndash from the 50th (median) to the 95th ndash allows WSDOT to track changes in reliable travel times over the years at a finer level in order to evaluate operational improvements more accurately Changes in the 80th and 90th percentiles are likely to represent travel times that are the result of routine incidents and other factors that the agency can influence with

5

5

90 405

167

512

3

305

104

16

520

522

9

203

202

2

2

18

525

Seattle Bellevue

Everett

Tacoma

Renton

Kent

Auburn

Puyallup

Lakewood

Federal Way

Mukilteo

Poulsbo

Bremerton

Purdy

Fife

Redmond

509

Pierce County

Pierce County Kitsap County

King County

King County

Snohomish County

Kitsap Peninsula

Vashon Island

BainbridgeIsland

PugetSound

Lake Washington

WhidbeyIsland

Sea-Tac Intrsquol Airport

Tacoma Narrows Bridge

167

Snoh

omish

County

Island

County

5

104

3

Freeway HOV amp HOT Lane System

HOV lanes operate 24 hours HOV lanes operate 24 hours 3+ HOV lanes operate 5 am - 7 pm HOV lanes in Reversible Express Lane Roadway (variable hours) HOT lanes operate 5 am - 7 pm Construction funded Construction unfunded or partially funded Direct Access Ramps ndash Open Direct Access Ramps ndash Open(Transit Only) Direct Access Ramps ndash Future

NOTE HOV lanes require two or morepeople (2+) unless otherwise notedHours of operation are for all seven daysof the week

T

T

Freeway HOV and HOT lane systems in the greater Puget Sound area

10 | WSDOT 2013 Corridor Capacity Report

operational strategies See pp 46-48 for detailed reliability data and pp 78-84 for more on operational strategies such as tolling Active Traffic Management Intelligent Transportation Systems (ITS) and Incident Response

WSDOT examines high occupancy vehicle (HOV) trip performance WSDOT uses several measures to evaluate HOV trip performance WSDOT and the Puget Sound Regional Council (PSRC) adopted a reliability standard for HOV lanes which states that for 90 of the peak hour HOV lanes should maintain an average speed of 45 mph This is the basis for WSDOTrsquos HOV reliability measure WSDOT also measures person throughput to gauge the effectiveness of HOV lanes in carrying more people compared to single occupancy vehicle (SOV) lanes and reports HOV trip travel times compared to SOV trip travel times

The map at left depicts the HOV and HOT lane system in the Puget Sound area About 310 lane-miles of the planned 320-mile Puget Sound area HOV network have been completed More information about the HOV lane network can be found starting on p 65 or at httpwwwwsdotwagovhov

Using Before and After analyses to review project performance As of June 30 2013 WSDOT completed 344 out of 421 projects funded by the 2003 and 2005 gas tax packages of which 91 were congestion relief projects To measure how well these investments are mitigating congestion WSDOT has implemented Before and After project studies to analyze impacts on travel times and delay On highway segments without in-pavement loop detectors data is collected using automated license plate recognition (ALPR) cameras blue tooth readers or moving test vehicles Before and After performance evaluations are performed on key congestion relief projects to evaluate the benefits of projects that improve system efficiency See pp 85-90

Quantifying Incident Response benefits WSDOT uses several measures to evaluate the performance of its Incident Response (IR) program Beginning in the 2011 Congestion Report WSDOT quantifies the annual economic benefits provided by the IR program For details on the IR program and how it helps alleviate non-recurrent congestion see pp 81-84

-

Dashboard of Indicators

2013 Corridor Capacity Report Dashboard of Indicators Difference Dollar values are inflation-adjusted measured in 2012 dollars 2007 2008 2009 2010 2011 2012 lsquo10 vs lsquo12

Demographic and economic indicators

State population (thousands) 6525 6608 6672 6725 6768 6818 14

Gasoline price per gallon (annual average)1 $329 $364 $276 $317 $380 $384 208

Washington unemployment rate (annual) 46 54 94 99 92 82 -17

Washington real per person income2 $46265 $46706 $44386 $44369 $45197 $45941 35

Multi-modal performance measures

Drive alone commuting rate3 731 715 721 730 733 - -

Carpooling commuting rate3 114 122 113 105 102 - -

Public transit commuting rate3 54 55 59 55 56 - -

Transit ridership4 (in millions) 1952 2156 2101 2078 2130 - -

Washington State Ferries ridership4 (in millions) 241 233 225 226 223 - -

Bicycling and walking commuting rate3 41 45 43 44 42 - -

Statewide congestion indicators

Per person total vehicle miles traveled on all public roads state highways only

All public roads vehicle miles traveled (VMT) in billions 56964 55447 56461 57191 56965 56607 -10

All public roads per person VMT in miles 8730 8391 8462 8505 8417 8303 -24

State highways VMT in billions 31970 30742 31456 31764 31455 31214 -17

State highways per person VMT in miles 4900 4652 4714 4724 4648 4578 -31

Congestion on state highway system

Total state highway lane miles 18425 18500 18571 18630 18642 18659 02

Lane miles of state highway system congested 1032 962 966 1025 1007 1026 00

Percent of state highway system congested5 56 52 52 55 54 55 00

Per person total and cost of delay on state highways

Annual hours of per person delay on state highways6 54 53 42 47 48 45 -43

Total vehicle hours of delay in millions of hours6 351 348 281 316 325 309 -24

Cost of delay on state highways (2012 dollars)6 $931 $890 $721 $800 $821 $780 -24

Corridor specific congestion indicators (52 central Puget Sound area commutes)

Annual Maximum Throughput Travel Time Index (MT3I)7 145 1258 130 139 135 139 00

Number of commute routes with MT3I gt 17 46 418 43 45 44 44

WSDOT congestion relief projects

Number of completed Nickel and TPA mobility projects as 33 43 73 91 65 82of December 31 of each year (cumulative)

Cumulative project value (dollars in millions) $963 $1289 $2212 $2596 $2802 $3851 $1255

Data source Washington State Office of Financial Management Economic and Revenue Forecast Council Bureau of Economic Analysis US Department of Energy - Energy Information Administration Bureau of Labor Statistics ndash Consumer Price Index WSDOT State Highway Log US Census Bureau - American Community Survey National Transit Database

Notes WSDOTrsquos annual Congestion Report is renamed as the Corridor Capacity Report beginning with the 2013 publication Analysis in the 2013 Corridor Capacity Report examines 2010 and 2012 annual data 2007 is included to show pre-recession levels All dollar values are inflation-adjusted using the Consumer Price Index (CPI) 1 Gas prices are reported in 2012 dollars and represent yearly averages 2 Real per capita income is measured as total statewide personal income in 2012 dollars divided by state population 3 Based on one-year estimates from the American Community Survey commuting rates are of workers age 16 and older 4 Ridership means the number of boardings also called unlinked passenger trips 5 Based on below 70 of posted speed 6 Based on maximum throughput speed threshold (85 of posted speed) 7 MT3I greater than one means the commute route experiences congestion 8 2008 data not available for four of the 52 routes For more information see gray box in the 2009 Congestion Report p 15

4 | WSDOT 2013 Corridor Capacity Report Dashboard of Indicators

-1

18

Introduction

Introduction

WSDOTrsquos Corridor Capacity Report presents detailed analysis for current and baseline years The Corridor Capacity Reportrsquos detailed analysis shows where and how much congestion occurs and whether it has grown on state highways The report focuses on the most traveled commute routes in the urban areas of the state ie central and south Puget Sound areas Vancouver Spokane and the Tri-Cities area and elsewhere around the state where data is available WSDOT and University of Washington experts use a two-year span to more accurately identify changes and trends seen on the state highway system that may be missed by looking at a one-year comparison For the 2013 Corridor Capacity Report calendar year 2012 is the current analysis year data while 2010 data is the baseline for comparison Some exceptions were made to use 2011 data in place of 2010 due to data availability and data quality

This year WSDOT is introducing new performance metrics listed below along with the standard metrics

Key congestion performance measures

Measure Definition

WSDOTrsquos congestion measurement principles Use real-time measurements (rather than computer

models) whenever and wherever possible

Use maximum throughput as the basis for congestion measures

Distinguish between and measure both congestion due to incidents (non-recurrent) and congestion due to inadequate capacity (recurrent)

Show how reducing non-recurrent congestion from incidents will improve the travel time reliability

Demonstrate both long-term trends and short-toshyintermediate-term results

Communicate possible congestion fixes using an ldquoapples-to-applesrdquo comparison with the current situation For example ldquoIf the trip takes 20 minutes today how many minutes less will it be if WSDOT improves the interchangerdquo

Use ldquoplain Englishrdquo to describe measurements and results

NEW Commute congestion cost Cost due to wasted fuel and time associated with travel during congested conditions (speeds slower than 45 mph) that could have been spent productively elsewhere

NEW Greenhouse gas emissions The pounds of carbon dioxide (CO2) emitted during peak period commutes The per-person emissions per trip during peak periods The emissions avoided by use of transit services

NEW Transit ridership and used Ridership on buses light rail and commuter rail during the peak periods between commute route capacity origins and destinations Used capacity in percent of available seats that are used on transit already

serving commute routes

NEW Park and Ride capacity and use Number of parking spaces and percent of capacity used on an average annual weekday

NEW Routinely congested segments Sections of roadway where traffic demand reaches capacity on at least 40 of the weekdays annually

Average peak travel time The average travel time on a route during the peak five-minute interval for all weekdays of the calendar year

95th percentile reliable travel time Travel time with 95 certainty (ie on-time 19 out of 20 work days)

Maximum Throughput Travel Time Index (MTsup3I) The ratio of average peak travel time compared to maximum throughput speed travel time

Percent of days when speeds are Percent of days annually that observed speeds for one or more five-minute interval is less than 36 mph less than 36 mph (severe congestion) on key highway segments

Vehicle throughput Measures how many vehicles move through a highway segmentspot location in an hour

Lost throughput productivity Percentage of a highwayrsquos lost vehicle throughput due to congestion when compared to the maximum five-minute weekday flow rate observed at a particular location of the highway for that calendar year

Per person delay (other forms of delay The average total daily hours of delay per person based on the maximum throughput speed (85 of such as total delay) posted speed) measured annually for weekdays

Percent of the system congested Percent of total state highway lane miles that drop below 70 of the posted speed limit

Duration of congestion The time period in minutes when speeds fall below 45 mph

HOV lane reliability An HOV lane is deemed ldquoreliablerdquo as long as it maintains an average speed of 45 mph for 90 of the peak hour

Person throughput Measures how many people on average move through a highway segment during peak periods

Before and After analysis Before and After performance analysis of selected highway congestion relief projects and strategies

Average incident clearance time Operational measure defined as the time from notification of the incident until the last responder has left (Statewide) the scene for all incidents responded to by WSDOT Incident Response personnel statewide

WSDOT 2013 Corridor Capacity Report | 5

2012 greenhouse gas emissions factors for four categories of vehicles decline with increasing speed Carbon dioxide emissions in pounds of CO2 per vehicle mile traveled Speed in miles per hour

Introduction

Introduction

Measuring cost of congestion greenhouse gas emissions and transit

WSDOTrsquos new multi-modal system performance measures include commute congestion cost trip-based vehicle emissions transit usage park and ride lot capacity and use and locations that experience routine congestion

NEW WSDOT quantifies the congestion cost for individuals and commutes With the 2013 Corridor Capacity Report WSDOT is for the first time quantifying commute congestion cost at the individual commuter level to answer the question ldquohow much does congestion cost a daily commuterrdquo Commute congestion cost is based on the duration of congestion that represents the timeframe during which users can expect to travel at speeds below 45 mph (75 of posted speed) during their daily commute While daily commuters may build extra time and operating costs into their routines and budgets to account for traveling during congested periods congestion still represents costs lost opportunities and lost productivity that negatively affect individuals and society

Commute congestion cost = (Average travel time ndash Travel time at threshold speed) X Traffic volume within the duration of congestion X Cost of travel

Commute congestion cost is computed for every five-minute interval within the time that a particular commute is experiencing congestion This methodology underestimates commute congestion cost because it does not capture the periodic slowdowns (when speeds drop below 45 mph) briefly experienced during individual trips along the length of the commute Commute congestion cost can be estimated using the equation above

NEW WSDOT quantifies greenhouse gas emissions from commuters on central Puget Sound area routes WSDOTrsquos new metric captures the approximate pounds of carbon dioxide (CO2) emitted during a one-way commute trip Total emissions during the peak period are reported along with the emissions per person The per-person metric takes into consideration the average number of people in each vehicle in the single-occupancy vehicle lanes

CO2 emissions from vehicles are directly related to the speed at which the vehicle is traveling For speeds slower than 25 mph the emissions quickly escalate to more than five times as many pounds of CO2 per mile compared to at faster speeds (see example graph above right) However there is little variation in emissions per vehicle mile traveled between

Example greenhouse gas emissions factors for four categories of vehicles decline with increasing speed Carbon dioxide emissions in pounds of CO2 per vehicle mile traveled Speed in miles per hour 25

0

5

10

15

20

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75

Transit buses

Passenger car amp truck

Medium trucks

Heavy trucks

Data source Puget Sound Regional Council

Note Factors for 2012 restricted access urban roadways Emissions factors do not reflect relative emissions per person mile traveled by the different modes of transportation

35 and 65 mph the typical range of speeds on Washington highways Emissions also vary by the type of vehicles medium and large trucks emit more CO2 per mile than a typical passenger car Total emissions on a roadway during the peak period fluctuate more with the volume of vehicles on the roadway year to year than with the changes in average speed unless the average speeds are slower than 25 mph

CO2 emissions are computed for every five-minute interval within the morning or evening peak period applying emission factors based on the mix of trucks and passenger vehicles and the average speed during that time CO2

emissions can be estimated using the equation below

CO2 emissions during peak period = Sum for every 5 minutes during peak period ((Truck X Truck emission factor) + (1 - Truck) X Car emission factor) X Traffic volume within the 5-minute interval X Trip length)

Per person per trip CO2 emissions are calculated using the emissions during the peak period the average number of people in each vehicle in the single-occupancy vehicle lanes and the total traffic volume on the commute corridor during the peak period The per-person emissions can be estimated using the equation below

CO2 per person trip = (CO2 emissions during peak period) (Traffic volume during peak period X Average observed trip vehicle occupancy)

Emissions avoided by transit use are estimated with the following equation for commute trips during the peak periods

CO2 avoided = Number of transit riders during peak period X 062 SOV miles avoided per transit passenger mile X Trip length X 10 pound of CO2 per mile traveled

6 | WSDOT 2013 Corridor Capacity Report

Introduction

Introduction

WSDOTrsquos congestion measurement principles in action

NEW Quantifying the transit use along central Puget Sound area commute routes WSDOT for the first time measures system capacity across modes along the central Puget Sound area commute routes This includes the utilization of the HOV lanes compared to adjacent SOV lanes (see person-throughput analysis on p 66) and the capacity used on public transit services Sound Transit King County Metro and Community Transit provide public transportation services throughout the central Puget Sound area WSDOT aligned the bus light rail and Sounder commuter rail routes with the 40 peak period commute trips (see pp 49-52) WSDOT computed average daily transit statistics for each commute for ridership average load (percent of seats used) vehicle trips off the SOV lanes and greenhouse gas emissions avoided by transit ridership

NEW Park and ride lot use supports transit Park and ride (PampR) lots provide locations for a commuter to meet up with carpool or vanpool participants or to catch a bus to work if transit does not come close to their home WSDOT tracks the average percent of available space used PampR lots at or near capacity discourage potential transit users and ridesharers because they do not have a reliable place to park

NEW Routinely congested segments illustrate where demand exceeds capacity Specific sections of the urban highway system experience routine congestion due to constrained conditions WSDOT tracks how often demand exceeds capacity on the highway system and documents the frequency and length of time (duration) the route is congested This type of congestion is not related to incidents or collisions although such occurrences accentuate the regular congestion

NEW WSDOT expands commute trip analysis coverage around the state WSDOTrsquos 2013 Corridor Capacity Report expands the commute trip analysis coverage to include south Puget Sound and Vancouver area commute trips in addition to trips in the central Puget Sound and Spokane areas This brings the total to 82 commute trips analyzed statewide

WSDOT collects real-time traffic data WSDOT collects real-time data for all 82 commute routes in urban areas around the state including the central and south Puget Sound areas (52 and 20 routes respectively) the Vancouver area (8 routes) the Spokane area (2 routes) and on other highways statewide

In the central Puget Sound area alone data is collected from about 6800 loop detectors embedded in the pavement throughout 235 centerline miles (1300 lane miles) Similarly the south Puget Sound area has 128 active data sensors that stretch along 77 centerline miles (270 lane miles) Other urban areas of the state have loop detectors and other technologies used for traffic data collection WSDOT for the first time uses private sector speed data for Vancouver area commute trip analysis to complement the existing WSDOT data set

The data collected from these WSDOT loop detectors are quality controlled using a variety of software processes WSDOT uses this data to analyze system performance In tracking and communicating performance results WSDOT adheres to congestion measurement principles including the use of more accurate real-time data rather than modeled data and uses language and terminology that is meaningful to the public (ldquoplain Englishrdquo) See p 5 for a list of performance measures and principles

Measures that matter to drivers speed travel time and reliability Speed is a metric that carries importance not only with WSDOT but with the general public as well Measuring the time to get from point A to point B is one of the most easily understood congestion measures Travel time reliability also matters to commuters and businesses because it is important for people and goods to be on time all the time

WSDOTrsquos Corridor Capacity Report examines travel times on the 82 commute trips around the state with a particular focus on 40 high-demand routes in the central Puget Sound area Travel times for high occupancy vehicle (HOV) lanes along many of these same corridors are also reported

The metrics used in the commute trip analysis include the average peak travel time the 95th percentile reliable travel time the duration of congestion and the percent of weekdays when average travel speeds are below 36 mph The performance of an individual route compares data with the current analysis year to the baseline year

WSDOTrsquos previously published person-based measures (per capita for statewide measures) include per person vehicle miles traveled and per person hours of delay in traffic (statewide urban area and corridor based) along with the per person trip travel time on commute corridors

WSDOT expanded reliability analysis looks at a range

WSDOT 2013 Corridor Capacity Report | 7

Introduction

Introduction

How do WSDOTrsquos congestion performance measures work

of travel time percentiles in the 2009 Congestion Report This analysis allows WSDOT to examine travel time changes at a finer level of detail and better evaluate its operational strategies

Real-time travel times for key commute routes in central and south Puget Sound areas Spokane and Vancouver are available to the public and updated every 5 minutes on the WSDOT website at www wsdotwagovtrafficseattletraveltimes

Measuring vehicle miles traveled (VMT) WSDOT examines vehicle miles traveled (VMT) as a volume metric for each commute route VMT is calculated for peak hours for the commute routes and all-day VMT is reported as part of the statewide metric WSDOT examines factors such as the use of public transportation population change unemployment rates real personal income and fuel prices as they relate to volume and travel time changes

VMT allows WSDOT to quantify travel along a route Because traffic volumes vary along a route each locationrsquos traffic volume is multiplied by the representative length of the route and these values are added up to obtain a routersquos total VMT WSDOT uses this measure to better understand the number of trips taken on certain commute routes and the total miles traveled on state highways This helps WSDOT predict future demand and establish improvement needs

Traffic volume is a vehicle count at a given roadway location It is measured by a detector in each lane at the location WSDOT has loop detectors spaced at roughly half-mile intervals throughout the central Puget Sound area freeway network and at various locations on the highway system statewide

WSDOT uses maximum throughput to measure congestion performance To operate the highway system as efficiently as possible the speed at which the highest number of vehicles can move through a highway segment (maximum throughput) is more meaningful than posted speed as the basis of measurement WSDOT aims to provide and maintain a system that yields the most productivity and efficiency rather than a system that is free flowing but where fewer vehicles can pass through a segment during peak travel periods

Understanding maximum throughput An adaptation of the Understanding maximum throughput An adaptation speedvolume curve of the speedvolume curveMay 2010 weekday volume 6-10 am I-405 NB at 24th NE I-405 northbound at 24th NE 6-10 am weekdays volume in May 2010Speed limit 60 mph Maximum throughput speed ranges between Speed limit 60 mph Maximum throughput speed ranges between70 and 85 of posted speed 70-85 of posted speed

When few vehicles use a70 mph highway they can all travel

0 mph

10 mph

20 mph

30 mph

40 mph

50 mph

60 mph near the speed limit

Maximum throughput

As still more vehicles use a highway all traffic slows and capacitydecreases

If more vehicles use a highway traffic slows but capacity remains high

If too many vehicles usea highway congestion greatly reduces capacity

0 500 1000 1500 2000 2500 Volume of vehicles per hour per lane

Data source WSDOT Northwest Region Traffic Office

Maximum throughput is achieved when vehicles travel at speeds between 42 and 51 mph (roughly 70 to 85 of a posted 60 mph speed) At maximum throughput speeds highways are operating at peak efficiency because more vehicles are passing through the segment than at posted speeds This happens because drivers at maximum throughput speeds can safely travel with a shorter distance between vehicles than they can at posted speeds

Maximum throughput speeds vary from one highway segment to the next depending on prevailing roadway design (roadway alignment lane width slope shoulder width pavement conditions presence or absence of median barriers) and traffic conditions (traffic composition conflicting traffic movements heavy truck traffic etc) The maximum throughput speed is not static and can change over time as conditions change Ideally maximum throughput speeds for each highway segment should be determined through comprehensive traffic studies and validated by field surveys For surface arterials (interrupted flow facilities) maximum throughput speeds are difficult to predict because they are influenced by interruptions in flow due to the conflicting traffic movements at intersections

WSDOT uses the maximum throughput standard as a basis for measurement to assess travel delay relative to a highwayrsquos most efficient condition at maximum throughput speeds (85 of posted speed) For more information on changes in travel delay performance please see pp 42-64

8 | WSDOT 2013 Corridor Capacity Report

Introduction

Introduction

WSDOT thresholds for system efficiency maximum throughput

WSDOT also uses maximum throughput as a basis for evaluating the system through the following measures

Total delay and per person delay

Percent of the system that is delayed and congested

Lost throughput productivity

Maximum Throughput Travel Time IndexmdashMT3I (for a more detailed discussion see p 46)

Duration of the congested period

Commute congestion cost

Measuring per person delay and total delay Delay can be measured at various speed thresholds such as free flow speed posted speed or maximum throughput speeds WSDOT uses maximum throughput speeds rather than free flow or posted speeds to measure delay relative to the highwayrsquos most efficient operating condition WSDOT measures travel delay statewide and on five major commute corridors in the central Puget Sound area In addition to measuring total hours of delay WSDOT also evaluates annual per person delay and the cost of delay to drivers and businesses

Measuring the percentage of the highway system that is delayed This measure allows WSDOT to assess the percentage of its system that is operating below maximum throughput speed creating delay for the traveling public The metric is

calculated for an average weekday by dividing the number of lane miles where speeds drop below 85 of posted speeds by total lane miles It allows differentiation between delayed lane miles in urban and rural areas of the state

Measuring the percentage of the highway system that is congested This measure allows WSDOT to evaluate what percentage of the system that the agency manages is congested It is calculated for an annual average weekday by dividing the number of lane miles where speeds drop below 70 of posted speeds by total lane miles This measure also differentiates between the portion of congested lane miles in urban versus rural areas of the state

Evaluating vehicle throughput productivity Highways are engineered to move specific volumes of vehicles based on the number of lanes and other design aspects Highways are not necessarily operating at their maximum efficiency when all vehicles are moving at 60 mph (the typical urban highway posted speed limit in Washington) As congestion increases speeds decrease and fewer vehicles pass through the corridor Throughput productivity may decline from a maximum of about 2000 vehicles per hour per lane traveling at speeds between 42 and 51 mph (100 efficiency) to as low as 700 vehicles per hour per lane (35 efficiency) at speeds less than 30 mph

WSDOT state highway speed thresholds for congestion measurement

Measure Threshold Description

Posted speed 60 mph Vehicles are moving through a highway segment at the posted speed but to travel safely at higher speeds and allow sufficient stopping distance drivers must maintain more space between vehicles Fewer vehicles can pass through the segment in a given amount of time and the segment is not operating at maximum efficiency

Maximum throughput speed (optimal flow speed)

70-85 of posted speed (about 42-51 mph)

Vehicles are moving slower than the posted speed and the number of vehicles moving through the highway segment is higher These speed conditions enable the segment to reach its maximum productivity in terms of vehicle volume and throughput (based on the speedvolume curve) This threshold range is used for highway system deficiency analysis

Duration of congested period (urban commute routes)

Duration of time vehicle speeds drop below 75 of posted speeds (45 mph)

The average weekday peak time period (in minutes) when average vehicle speeds drop below 75 of posted speeds (about 45 mph) Drivers have less than optimal spacing between cars and the number of vehicles that can move through a highway segment is reduced The highway begins to operate less efficiently under these conditions than at maximum throughput

Percent of state highway system delayed

Less than 85 of posted speeds

Percent of total state highway lane miles that drop below 85 of the posted speed limit

Percent of state highway system congested

Less than 70 of posted speeds

Percent of total state highway lane miles that drop below 70 of the posted speed limit

Severe congestion

Less than 60 of posted speed (less than 36 mph)

Speeds and spacing between vehicles continue to decline on a highway segment and highway efficiency operates well below maximum productivity

WSDOT 2013 Corridor Capacity Report | 9

Introduction

Introduction

Measuring per person delay vehicle throughput reliability

Measuring travel time reliability WSDOT uses the 95th percentile reliable travel time as its key reliability metric for the 82 commute trips monitored statewide Travel time reliability is measured in percentiles For example 95th percentile travel times track the amount of time a traveler will need to plan in order to be on time 95 of the time (19 of 20 weekday trips) 80th percentile travel times will ensure the traveler is on time four out of five weekday trips A benefit to using percentile measures is they are not affected by outlier values generally the longest travel times Using a range of percentiles ndash from the 50th (median) to the 95th ndash allows WSDOT to track changes in reliable travel times over the years at a finer level in order to evaluate operational improvements more accurately Changes in the 80th and 90th percentiles are likely to represent travel times that are the result of routine incidents and other factors that the agency can influence with

5

5

90 405

167

512

3

305

104

16

520

522

9

203

202

2

2

18

525

Seattle Bellevue

Everett

Tacoma

Renton

Kent

Auburn

Puyallup

Lakewood

Federal Way

Mukilteo

Poulsbo

Bremerton

Purdy

Fife

Redmond

509

Pierce County

Pierce County Kitsap County

King County

King County

Snohomish County

Kitsap Peninsula

Vashon Island

BainbridgeIsland

PugetSound

Lake Washington

WhidbeyIsland

Sea-Tac Intrsquol Airport

Tacoma Narrows Bridge

167

Snoh

omish

County

Island

County

5

104

3

Freeway HOV amp HOT Lane System

HOV lanes operate 24 hours HOV lanes operate 24 hours 3+ HOV lanes operate 5 am - 7 pm HOV lanes in Reversible Express Lane Roadway (variable hours) HOT lanes operate 5 am - 7 pm Construction funded Construction unfunded or partially funded Direct Access Ramps ndash Open Direct Access Ramps ndash Open(Transit Only) Direct Access Ramps ndash Future

NOTE HOV lanes require two or morepeople (2+) unless otherwise notedHours of operation are for all seven daysof the week

T

T

Freeway HOV and HOT lane systems in the greater Puget Sound area

10 | WSDOT 2013 Corridor Capacity Report

operational strategies See pp 46-48 for detailed reliability data and pp 78-84 for more on operational strategies such as tolling Active Traffic Management Intelligent Transportation Systems (ITS) and Incident Response

WSDOT examines high occupancy vehicle (HOV) trip performance WSDOT uses several measures to evaluate HOV trip performance WSDOT and the Puget Sound Regional Council (PSRC) adopted a reliability standard for HOV lanes which states that for 90 of the peak hour HOV lanes should maintain an average speed of 45 mph This is the basis for WSDOTrsquos HOV reliability measure WSDOT also measures person throughput to gauge the effectiveness of HOV lanes in carrying more people compared to single occupancy vehicle (SOV) lanes and reports HOV trip travel times compared to SOV trip travel times

The map at left depicts the HOV and HOT lane system in the Puget Sound area About 310 lane-miles of the planned 320-mile Puget Sound area HOV network have been completed More information about the HOV lane network can be found starting on p 65 or at httpwwwwsdotwagovhov

Using Before and After analyses to review project performance As of June 30 2013 WSDOT completed 344 out of 421 projects funded by the 2003 and 2005 gas tax packages of which 91 were congestion relief projects To measure how well these investments are mitigating congestion WSDOT has implemented Before and After project studies to analyze impacts on travel times and delay On highway segments without in-pavement loop detectors data is collected using automated license plate recognition (ALPR) cameras blue tooth readers or moving test vehicles Before and After performance evaluations are performed on key congestion relief projects to evaluate the benefits of projects that improve system efficiency See pp 85-90

Quantifying Incident Response benefits WSDOT uses several measures to evaluate the performance of its Incident Response (IR) program Beginning in the 2011 Congestion Report WSDOT quantifies the annual economic benefits provided by the IR program For details on the IR program and how it helps alleviate non-recurrent congestion see pp 81-84

Introduction

Introduction

WSDOTrsquos Corridor Capacity Report presents detailed analysis for current and baseline years The Corridor Capacity Reportrsquos detailed analysis shows where and how much congestion occurs and whether it has grown on state highways The report focuses on the most traveled commute routes in the urban areas of the state ie central and south Puget Sound areas Vancouver Spokane and the Tri-Cities area and elsewhere around the state where data is available WSDOT and University of Washington experts use a two-year span to more accurately identify changes and trends seen on the state highway system that may be missed by looking at a one-year comparison For the 2013 Corridor Capacity Report calendar year 2012 is the current analysis year data while 2010 data is the baseline for comparison Some exceptions were made to use 2011 data in place of 2010 due to data availability and data quality

This year WSDOT is introducing new performance metrics listed below along with the standard metrics

Key congestion performance measures

Measure Definition

WSDOTrsquos congestion measurement principles Use real-time measurements (rather than computer

models) whenever and wherever possible

Use maximum throughput as the basis for congestion measures

Distinguish between and measure both congestion due to incidents (non-recurrent) and congestion due to inadequate capacity (recurrent)

Show how reducing non-recurrent congestion from incidents will improve the travel time reliability

Demonstrate both long-term trends and short-toshyintermediate-term results

Communicate possible congestion fixes using an ldquoapples-to-applesrdquo comparison with the current situation For example ldquoIf the trip takes 20 minutes today how many minutes less will it be if WSDOT improves the interchangerdquo

Use ldquoplain Englishrdquo to describe measurements and results

NEW Commute congestion cost Cost due to wasted fuel and time associated with travel during congested conditions (speeds slower than 45 mph) that could have been spent productively elsewhere

NEW Greenhouse gas emissions The pounds of carbon dioxide (CO2) emitted during peak period commutes The per-person emissions per trip during peak periods The emissions avoided by use of transit services

NEW Transit ridership and used Ridership on buses light rail and commuter rail during the peak periods between commute route capacity origins and destinations Used capacity in percent of available seats that are used on transit already

serving commute routes

NEW Park and Ride capacity and use Number of parking spaces and percent of capacity used on an average annual weekday

NEW Routinely congested segments Sections of roadway where traffic demand reaches capacity on at least 40 of the weekdays annually

Average peak travel time The average travel time on a route during the peak five-minute interval for all weekdays of the calendar year

95th percentile reliable travel time Travel time with 95 certainty (ie on-time 19 out of 20 work days)

Maximum Throughput Travel Time Index (MTsup3I) The ratio of average peak travel time compared to maximum throughput speed travel time

Percent of days when speeds are Percent of days annually that observed speeds for one or more five-minute interval is less than 36 mph less than 36 mph (severe congestion) on key highway segments

Vehicle throughput Measures how many vehicles move through a highway segmentspot location in an hour

Lost throughput productivity Percentage of a highwayrsquos lost vehicle throughput due to congestion when compared to the maximum five-minute weekday flow rate observed at a particular location of the highway for that calendar year

Per person delay (other forms of delay The average total daily hours of delay per person based on the maximum throughput speed (85 of such as total delay) posted speed) measured annually for weekdays

Percent of the system congested Percent of total state highway lane miles that drop below 70 of the posted speed limit

Duration of congestion The time period in minutes when speeds fall below 45 mph

HOV lane reliability An HOV lane is deemed ldquoreliablerdquo as long as it maintains an average speed of 45 mph for 90 of the peak hour

Person throughput Measures how many people on average move through a highway segment during peak periods

Before and After analysis Before and After performance analysis of selected highway congestion relief projects and strategies

Average incident clearance time Operational measure defined as the time from notification of the incident until the last responder has left (Statewide) the scene for all incidents responded to by WSDOT Incident Response personnel statewide

WSDOT 2013 Corridor Capacity Report | 5

2012 greenhouse gas emissions factors for four categories of vehicles decline with increasing speed Carbon dioxide emissions in pounds of CO2 per vehicle mile traveled Speed in miles per hour

Introduction

Introduction

Measuring cost of congestion greenhouse gas emissions and transit

WSDOTrsquos new multi-modal system performance measures include commute congestion cost trip-based vehicle emissions transit usage park and ride lot capacity and use and locations that experience routine congestion

NEW WSDOT quantifies the congestion cost for individuals and commutes With the 2013 Corridor Capacity Report WSDOT is for the first time quantifying commute congestion cost at the individual commuter level to answer the question ldquohow much does congestion cost a daily commuterrdquo Commute congestion cost is based on the duration of congestion that represents the timeframe during which users can expect to travel at speeds below 45 mph (75 of posted speed) during their daily commute While daily commuters may build extra time and operating costs into their routines and budgets to account for traveling during congested periods congestion still represents costs lost opportunities and lost productivity that negatively affect individuals and society

Commute congestion cost = (Average travel time ndash Travel time at threshold speed) X Traffic volume within the duration of congestion X Cost of travel

Commute congestion cost is computed for every five-minute interval within the time that a particular commute is experiencing congestion This methodology underestimates commute congestion cost because it does not capture the periodic slowdowns (when speeds drop below 45 mph) briefly experienced during individual trips along the length of the commute Commute congestion cost can be estimated using the equation above

NEW WSDOT quantifies greenhouse gas emissions from commuters on central Puget Sound area routes WSDOTrsquos new metric captures the approximate pounds of carbon dioxide (CO2) emitted during a one-way commute trip Total emissions during the peak period are reported along with the emissions per person The per-person metric takes into consideration the average number of people in each vehicle in the single-occupancy vehicle lanes

CO2 emissions from vehicles are directly related to the speed at which the vehicle is traveling For speeds slower than 25 mph the emissions quickly escalate to more than five times as many pounds of CO2 per mile compared to at faster speeds (see example graph above right) However there is little variation in emissions per vehicle mile traveled between

Example greenhouse gas emissions factors for four categories of vehicles decline with increasing speed Carbon dioxide emissions in pounds of CO2 per vehicle mile traveled Speed in miles per hour 25

0

5

10

15

20

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75

Transit buses

Passenger car amp truck

Medium trucks

Heavy trucks

Data source Puget Sound Regional Council

Note Factors for 2012 restricted access urban roadways Emissions factors do not reflect relative emissions per person mile traveled by the different modes of transportation

35 and 65 mph the typical range of speeds on Washington highways Emissions also vary by the type of vehicles medium and large trucks emit more CO2 per mile than a typical passenger car Total emissions on a roadway during the peak period fluctuate more with the volume of vehicles on the roadway year to year than with the changes in average speed unless the average speeds are slower than 25 mph

CO2 emissions are computed for every five-minute interval within the morning or evening peak period applying emission factors based on the mix of trucks and passenger vehicles and the average speed during that time CO2

emissions can be estimated using the equation below

CO2 emissions during peak period = Sum for every 5 minutes during peak period ((Truck X Truck emission factor) + (1 - Truck) X Car emission factor) X Traffic volume within the 5-minute interval X Trip length)

Per person per trip CO2 emissions are calculated using the emissions during the peak period the average number of people in each vehicle in the single-occupancy vehicle lanes and the total traffic volume on the commute corridor during the peak period The per-person emissions can be estimated using the equation below

CO2 per person trip = (CO2 emissions during peak period) (Traffic volume during peak period X Average observed trip vehicle occupancy)

Emissions avoided by transit use are estimated with the following equation for commute trips during the peak periods

CO2 avoided = Number of transit riders during peak period X 062 SOV miles avoided per transit passenger mile X Trip length X 10 pound of CO2 per mile traveled

6 | WSDOT 2013 Corridor Capacity Report

Introduction

Introduction

WSDOTrsquos congestion measurement principles in action

NEW Quantifying the transit use along central Puget Sound area commute routes WSDOT for the first time measures system capacity across modes along the central Puget Sound area commute routes This includes the utilization of the HOV lanes compared to adjacent SOV lanes (see person-throughput analysis on p 66) and the capacity used on public transit services Sound Transit King County Metro and Community Transit provide public transportation services throughout the central Puget Sound area WSDOT aligned the bus light rail and Sounder commuter rail routes with the 40 peak period commute trips (see pp 49-52) WSDOT computed average daily transit statistics for each commute for ridership average load (percent of seats used) vehicle trips off the SOV lanes and greenhouse gas emissions avoided by transit ridership

NEW Park and ride lot use supports transit Park and ride (PampR) lots provide locations for a commuter to meet up with carpool or vanpool participants or to catch a bus to work if transit does not come close to their home WSDOT tracks the average percent of available space used PampR lots at or near capacity discourage potential transit users and ridesharers because they do not have a reliable place to park

NEW Routinely congested segments illustrate where demand exceeds capacity Specific sections of the urban highway system experience routine congestion due to constrained conditions WSDOT tracks how often demand exceeds capacity on the highway system and documents the frequency and length of time (duration) the route is congested This type of congestion is not related to incidents or collisions although such occurrences accentuate the regular congestion

NEW WSDOT expands commute trip analysis coverage around the state WSDOTrsquos 2013 Corridor Capacity Report expands the commute trip analysis coverage to include south Puget Sound and Vancouver area commute trips in addition to trips in the central Puget Sound and Spokane areas This brings the total to 82 commute trips analyzed statewide

WSDOT collects real-time traffic data WSDOT collects real-time data for all 82 commute routes in urban areas around the state including the central and south Puget Sound areas (52 and 20 routes respectively) the Vancouver area (8 routes) the Spokane area (2 routes) and on other highways statewide

In the central Puget Sound area alone data is collected from about 6800 loop detectors embedded in the pavement throughout 235 centerline miles (1300 lane miles) Similarly the south Puget Sound area has 128 active data sensors that stretch along 77 centerline miles (270 lane miles) Other urban areas of the state have loop detectors and other technologies used for traffic data collection WSDOT for the first time uses private sector speed data for Vancouver area commute trip analysis to complement the existing WSDOT data set

The data collected from these WSDOT loop detectors are quality controlled using a variety of software processes WSDOT uses this data to analyze system performance In tracking and communicating performance results WSDOT adheres to congestion measurement principles including the use of more accurate real-time data rather than modeled data and uses language and terminology that is meaningful to the public (ldquoplain Englishrdquo) See p 5 for a list of performance measures and principles

Measures that matter to drivers speed travel time and reliability Speed is a metric that carries importance not only with WSDOT but with the general public as well Measuring the time to get from point A to point B is one of the most easily understood congestion measures Travel time reliability also matters to commuters and businesses because it is important for people and goods to be on time all the time

WSDOTrsquos Corridor Capacity Report examines travel times on the 82 commute trips around the state with a particular focus on 40 high-demand routes in the central Puget Sound area Travel times for high occupancy vehicle (HOV) lanes along many of these same corridors are also reported

The metrics used in the commute trip analysis include the average peak travel time the 95th percentile reliable travel time the duration of congestion and the percent of weekdays when average travel speeds are below 36 mph The performance of an individual route compares data with the current analysis year to the baseline year

WSDOTrsquos previously published person-based measures (per capita for statewide measures) include per person vehicle miles traveled and per person hours of delay in traffic (statewide urban area and corridor based) along with the per person trip travel time on commute corridors

WSDOT expanded reliability analysis looks at a range

WSDOT 2013 Corridor Capacity Report | 7

Introduction

Introduction

How do WSDOTrsquos congestion performance measures work

of travel time percentiles in the 2009 Congestion Report This analysis allows WSDOT to examine travel time changes at a finer level of detail and better evaluate its operational strategies

Real-time travel times for key commute routes in central and south Puget Sound areas Spokane and Vancouver are available to the public and updated every 5 minutes on the WSDOT website at www wsdotwagovtrafficseattletraveltimes

Measuring vehicle miles traveled (VMT) WSDOT examines vehicle miles traveled (VMT) as a volume metric for each commute route VMT is calculated for peak hours for the commute routes and all-day VMT is reported as part of the statewide metric WSDOT examines factors such as the use of public transportation population change unemployment rates real personal income and fuel prices as they relate to volume and travel time changes

VMT allows WSDOT to quantify travel along a route Because traffic volumes vary along a route each locationrsquos traffic volume is multiplied by the representative length of the route and these values are added up to obtain a routersquos total VMT WSDOT uses this measure to better understand the number of trips taken on certain commute routes and the total miles traveled on state highways This helps WSDOT predict future demand and establish improvement needs

Traffic volume is a vehicle count at a given roadway location It is measured by a detector in each lane at the location WSDOT has loop detectors spaced at roughly half-mile intervals throughout the central Puget Sound area freeway network and at various locations on the highway system statewide

WSDOT uses maximum throughput to measure congestion performance To operate the highway system as efficiently as possible the speed at which the highest number of vehicles can move through a highway segment (maximum throughput) is more meaningful than posted speed as the basis of measurement WSDOT aims to provide and maintain a system that yields the most productivity and efficiency rather than a system that is free flowing but where fewer vehicles can pass through a segment during peak travel periods

Understanding maximum throughput An adaptation of the Understanding maximum throughput An adaptation speedvolume curve of the speedvolume curveMay 2010 weekday volume 6-10 am I-405 NB at 24th NE I-405 northbound at 24th NE 6-10 am weekdays volume in May 2010Speed limit 60 mph Maximum throughput speed ranges between Speed limit 60 mph Maximum throughput speed ranges between70 and 85 of posted speed 70-85 of posted speed

When few vehicles use a70 mph highway they can all travel

0 mph

10 mph

20 mph

30 mph

40 mph

50 mph

60 mph near the speed limit

Maximum throughput

As still more vehicles use a highway all traffic slows and capacitydecreases

If more vehicles use a highway traffic slows but capacity remains high

If too many vehicles usea highway congestion greatly reduces capacity

0 500 1000 1500 2000 2500 Volume of vehicles per hour per lane

Data source WSDOT Northwest Region Traffic Office

Maximum throughput is achieved when vehicles travel at speeds between 42 and 51 mph (roughly 70 to 85 of a posted 60 mph speed) At maximum throughput speeds highways are operating at peak efficiency because more vehicles are passing through the segment than at posted speeds This happens because drivers at maximum throughput speeds can safely travel with a shorter distance between vehicles than they can at posted speeds

Maximum throughput speeds vary from one highway segment to the next depending on prevailing roadway design (roadway alignment lane width slope shoulder width pavement conditions presence or absence of median barriers) and traffic conditions (traffic composition conflicting traffic movements heavy truck traffic etc) The maximum throughput speed is not static and can change over time as conditions change Ideally maximum throughput speeds for each highway segment should be determined through comprehensive traffic studies and validated by field surveys For surface arterials (interrupted flow facilities) maximum throughput speeds are difficult to predict because they are influenced by interruptions in flow due to the conflicting traffic movements at intersections

WSDOT uses the maximum throughput standard as a basis for measurement to assess travel delay relative to a highwayrsquos most efficient condition at maximum throughput speeds (85 of posted speed) For more information on changes in travel delay performance please see pp 42-64

8 | WSDOT 2013 Corridor Capacity Report

Introduction

Introduction

WSDOT thresholds for system efficiency maximum throughput

WSDOT also uses maximum throughput as a basis for evaluating the system through the following measures

Total delay and per person delay

Percent of the system that is delayed and congested

Lost throughput productivity

Maximum Throughput Travel Time IndexmdashMT3I (for a more detailed discussion see p 46)

Duration of the congested period

Commute congestion cost

Measuring per person delay and total delay Delay can be measured at various speed thresholds such as free flow speed posted speed or maximum throughput speeds WSDOT uses maximum throughput speeds rather than free flow or posted speeds to measure delay relative to the highwayrsquos most efficient operating condition WSDOT measures travel delay statewide and on five major commute corridors in the central Puget Sound area In addition to measuring total hours of delay WSDOT also evaluates annual per person delay and the cost of delay to drivers and businesses

Measuring the percentage of the highway system that is delayed This measure allows WSDOT to assess the percentage of its system that is operating below maximum throughput speed creating delay for the traveling public The metric is

calculated for an average weekday by dividing the number of lane miles where speeds drop below 85 of posted speeds by total lane miles It allows differentiation between delayed lane miles in urban and rural areas of the state

Measuring the percentage of the highway system that is congested This measure allows WSDOT to evaluate what percentage of the system that the agency manages is congested It is calculated for an annual average weekday by dividing the number of lane miles where speeds drop below 70 of posted speeds by total lane miles This measure also differentiates between the portion of congested lane miles in urban versus rural areas of the state

Evaluating vehicle throughput productivity Highways are engineered to move specific volumes of vehicles based on the number of lanes and other design aspects Highways are not necessarily operating at their maximum efficiency when all vehicles are moving at 60 mph (the typical urban highway posted speed limit in Washington) As congestion increases speeds decrease and fewer vehicles pass through the corridor Throughput productivity may decline from a maximum of about 2000 vehicles per hour per lane traveling at speeds between 42 and 51 mph (100 efficiency) to as low as 700 vehicles per hour per lane (35 efficiency) at speeds less than 30 mph

WSDOT state highway speed thresholds for congestion measurement

Measure Threshold Description

Posted speed 60 mph Vehicles are moving through a highway segment at the posted speed but to travel safely at higher speeds and allow sufficient stopping distance drivers must maintain more space between vehicles Fewer vehicles can pass through the segment in a given amount of time and the segment is not operating at maximum efficiency

Maximum throughput speed (optimal flow speed)

70-85 of posted speed (about 42-51 mph)

Vehicles are moving slower than the posted speed and the number of vehicles moving through the highway segment is higher These speed conditions enable the segment to reach its maximum productivity in terms of vehicle volume and throughput (based on the speedvolume curve) This threshold range is used for highway system deficiency analysis

Duration of congested period (urban commute routes)

Duration of time vehicle speeds drop below 75 of posted speeds (45 mph)

The average weekday peak time period (in minutes) when average vehicle speeds drop below 75 of posted speeds (about 45 mph) Drivers have less than optimal spacing between cars and the number of vehicles that can move through a highway segment is reduced The highway begins to operate less efficiently under these conditions than at maximum throughput

Percent of state highway system delayed

Less than 85 of posted speeds

Percent of total state highway lane miles that drop below 85 of the posted speed limit

Percent of state highway system congested

Less than 70 of posted speeds

Percent of total state highway lane miles that drop below 70 of the posted speed limit

Severe congestion

Less than 60 of posted speed (less than 36 mph)

Speeds and spacing between vehicles continue to decline on a highway segment and highway efficiency operates well below maximum productivity

WSDOT 2013 Corridor Capacity Report | 9

Introduction

Introduction

Measuring per person delay vehicle throughput reliability

Measuring travel time reliability WSDOT uses the 95th percentile reliable travel time as its key reliability metric for the 82 commute trips monitored statewide Travel time reliability is measured in percentiles For example 95th percentile travel times track the amount of time a traveler will need to plan in order to be on time 95 of the time (19 of 20 weekday trips) 80th percentile travel times will ensure the traveler is on time four out of five weekday trips A benefit to using percentile measures is they are not affected by outlier values generally the longest travel times Using a range of percentiles ndash from the 50th (median) to the 95th ndash allows WSDOT to track changes in reliable travel times over the years at a finer level in order to evaluate operational improvements more accurately Changes in the 80th and 90th percentiles are likely to represent travel times that are the result of routine incidents and other factors that the agency can influence with

5

5

90 405

167

512

3

305

104

16

520

522

9

203

202

2

2

18

525

Seattle Bellevue

Everett

Tacoma

Renton

Kent

Auburn

Puyallup

Lakewood

Federal Way

Mukilteo

Poulsbo

Bremerton

Purdy

Fife

Redmond

509

Pierce County

Pierce County Kitsap County

King County

King County

Snohomish County

Kitsap Peninsula

Vashon Island

BainbridgeIsland

PugetSound

Lake Washington

WhidbeyIsland

Sea-Tac Intrsquol Airport

Tacoma Narrows Bridge

167

Snoh

omish

County

Island

County

5

104

3

Freeway HOV amp HOT Lane System

HOV lanes operate 24 hours HOV lanes operate 24 hours 3+ HOV lanes operate 5 am - 7 pm HOV lanes in Reversible Express Lane Roadway (variable hours) HOT lanes operate 5 am - 7 pm Construction funded Construction unfunded or partially funded Direct Access Ramps ndash Open Direct Access Ramps ndash Open(Transit Only) Direct Access Ramps ndash Future

NOTE HOV lanes require two or morepeople (2+) unless otherwise notedHours of operation are for all seven daysof the week

T

T

Freeway HOV and HOT lane systems in the greater Puget Sound area

10 | WSDOT 2013 Corridor Capacity Report

operational strategies See pp 46-48 for detailed reliability data and pp 78-84 for more on operational strategies such as tolling Active Traffic Management Intelligent Transportation Systems (ITS) and Incident Response

WSDOT examines high occupancy vehicle (HOV) trip performance WSDOT uses several measures to evaluate HOV trip performance WSDOT and the Puget Sound Regional Council (PSRC) adopted a reliability standard for HOV lanes which states that for 90 of the peak hour HOV lanes should maintain an average speed of 45 mph This is the basis for WSDOTrsquos HOV reliability measure WSDOT also measures person throughput to gauge the effectiveness of HOV lanes in carrying more people compared to single occupancy vehicle (SOV) lanes and reports HOV trip travel times compared to SOV trip travel times

The map at left depicts the HOV and HOT lane system in the Puget Sound area About 310 lane-miles of the planned 320-mile Puget Sound area HOV network have been completed More information about the HOV lane network can be found starting on p 65 or at httpwwwwsdotwagovhov

Using Before and After analyses to review project performance As of June 30 2013 WSDOT completed 344 out of 421 projects funded by the 2003 and 2005 gas tax packages of which 91 were congestion relief projects To measure how well these investments are mitigating congestion WSDOT has implemented Before and After project studies to analyze impacts on travel times and delay On highway segments without in-pavement loop detectors data is collected using automated license plate recognition (ALPR) cameras blue tooth readers or moving test vehicles Before and After performance evaluations are performed on key congestion relief projects to evaluate the benefits of projects that improve system efficiency See pp 85-90

Quantifying Incident Response benefits WSDOT uses several measures to evaluate the performance of its Incident Response (IR) program Beginning in the 2011 Congestion Report WSDOT quantifies the annual economic benefits provided by the IR program For details on the IR program and how it helps alleviate non-recurrent congestion see pp 81-84

2012 greenhouse gas emissions factors for four categories of vehicles decline with increasing speed Carbon dioxide emissions in pounds of CO2 per vehicle mile traveled Speed in miles per hour

Introduction

Introduction

Measuring cost of congestion greenhouse gas emissions and transit

WSDOTrsquos new multi-modal system performance measures include commute congestion cost trip-based vehicle emissions transit usage park and ride lot capacity and use and locations that experience routine congestion

NEW WSDOT quantifies the congestion cost for individuals and commutes With the 2013 Corridor Capacity Report WSDOT is for the first time quantifying commute congestion cost at the individual commuter level to answer the question ldquohow much does congestion cost a daily commuterrdquo Commute congestion cost is based on the duration of congestion that represents the timeframe during which users can expect to travel at speeds below 45 mph (75 of posted speed) during their daily commute While daily commuters may build extra time and operating costs into their routines and budgets to account for traveling during congested periods congestion still represents costs lost opportunities and lost productivity that negatively affect individuals and society

Commute congestion cost = (Average travel time ndash Travel time at threshold speed) X Traffic volume within the duration of congestion X Cost of travel

Commute congestion cost is computed for every five-minute interval within the time that a particular commute is experiencing congestion This methodology underestimates commute congestion cost because it does not capture the periodic slowdowns (when speeds drop below 45 mph) briefly experienced during individual trips along the length of the commute Commute congestion cost can be estimated using the equation above

NEW WSDOT quantifies greenhouse gas emissions from commuters on central Puget Sound area routes WSDOTrsquos new metric captures the approximate pounds of carbon dioxide (CO2) emitted during a one-way commute trip Total emissions during the peak period are reported along with the emissions per person The per-person metric takes into consideration the average number of people in each vehicle in the single-occupancy vehicle lanes

CO2 emissions from vehicles are directly related to the speed at which the vehicle is traveling For speeds slower than 25 mph the emissions quickly escalate to more than five times as many pounds of CO2 per mile compared to at faster speeds (see example graph above right) However there is little variation in emissions per vehicle mile traveled between

Example greenhouse gas emissions factors for four categories of vehicles decline with increasing speed Carbon dioxide emissions in pounds of CO2 per vehicle mile traveled Speed in miles per hour 25

0

5

10

15

20

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75

Transit buses

Passenger car amp truck

Medium trucks

Heavy trucks

Data source Puget Sound Regional Council

Note Factors for 2012 restricted access urban roadways Emissions factors do not reflect relative emissions per person mile traveled by the different modes of transportation

35 and 65 mph the typical range of speeds on Washington highways Emissions also vary by the type of vehicles medium and large trucks emit more CO2 per mile than a typical passenger car Total emissions on a roadway during the peak period fluctuate more with the volume of vehicles on the roadway year to year than with the changes in average speed unless the average speeds are slower than 25 mph

CO2 emissions are computed for every five-minute interval within the morning or evening peak period applying emission factors based on the mix of trucks and passenger vehicles and the average speed during that time CO2

emissions can be estimated using the equation below

CO2 emissions during peak period = Sum for every 5 minutes during peak period ((Truck X Truck emission factor) + (1 - Truck) X Car emission factor) X Traffic volume within the 5-minute interval X Trip length)

Per person per trip CO2 emissions are calculated using the emissions during the peak period the average number of people in each vehicle in the single-occupancy vehicle lanes and the total traffic volume on the commute corridor during the peak period The per-person emissions can be estimated using the equation below

CO2 per person trip = (CO2 emissions during peak period) (Traffic volume during peak period X Average observed trip vehicle occupancy)

Emissions avoided by transit use are estimated with the following equation for commute trips during the peak periods

CO2 avoided = Number of transit riders during peak period X 062 SOV miles avoided per transit passenger mile X Trip length X 10 pound of CO2 per mile traveled

6 | WSDOT 2013 Corridor Capacity Report

Introduction

Introduction

WSDOTrsquos congestion measurement principles in action

NEW Quantifying the transit use along central Puget Sound area commute routes WSDOT for the first time measures system capacity across modes along the central Puget Sound area commute routes This includes the utilization of the HOV lanes compared to adjacent SOV lanes (see person-throughput analysis on p 66) and the capacity used on public transit services Sound Transit King County Metro and Community Transit provide public transportation services throughout the central Puget Sound area WSDOT aligned the bus light rail and Sounder commuter rail routes with the 40 peak period commute trips (see pp 49-52) WSDOT computed average daily transit statistics for each commute for ridership average load (percent of seats used) vehicle trips off the SOV lanes and greenhouse gas emissions avoided by transit ridership

NEW Park and ride lot use supports transit Park and ride (PampR) lots provide locations for a commuter to meet up with carpool or vanpool participants or to catch a bus to work if transit does not come close to their home WSDOT tracks the average percent of available space used PampR lots at or near capacity discourage potential transit users and ridesharers because they do not have a reliable place to park

NEW Routinely congested segments illustrate where demand exceeds capacity Specific sections of the urban highway system experience routine congestion due to constrained conditions WSDOT tracks how often demand exceeds capacity on the highway system and documents the frequency and length of time (duration) the route is congested This type of congestion is not related to incidents or collisions although such occurrences accentuate the regular congestion

NEW WSDOT expands commute trip analysis coverage around the state WSDOTrsquos 2013 Corridor Capacity Report expands the commute trip analysis coverage to include south Puget Sound and Vancouver area commute trips in addition to trips in the central Puget Sound and Spokane areas This brings the total to 82 commute trips analyzed statewide

WSDOT collects real-time traffic data WSDOT collects real-time data for all 82 commute routes in urban areas around the state including the central and south Puget Sound areas (52 and 20 routes respectively) the Vancouver area (8 routes) the Spokane area (2 routes) and on other highways statewide

In the central Puget Sound area alone data is collected from about 6800 loop detectors embedded in the pavement throughout 235 centerline miles (1300 lane miles) Similarly the south Puget Sound area has 128 active data sensors that stretch along 77 centerline miles (270 lane miles) Other urban areas of the state have loop detectors and other technologies used for traffic data collection WSDOT for the first time uses private sector speed data for Vancouver area commute trip analysis to complement the existing WSDOT data set

The data collected from these WSDOT loop detectors are quality controlled using a variety of software processes WSDOT uses this data to analyze system performance In tracking and communicating performance results WSDOT adheres to congestion measurement principles including the use of more accurate real-time data rather than modeled data and uses language and terminology that is meaningful to the public (ldquoplain Englishrdquo) See p 5 for a list of performance measures and principles

Measures that matter to drivers speed travel time and reliability Speed is a metric that carries importance not only with WSDOT but with the general public as well Measuring the time to get from point A to point B is one of the most easily understood congestion measures Travel time reliability also matters to commuters and businesses because it is important for people and goods to be on time all the time

WSDOTrsquos Corridor Capacity Report examines travel times on the 82 commute trips around the state with a particular focus on 40 high-demand routes in the central Puget Sound area Travel times for high occupancy vehicle (HOV) lanes along many of these same corridors are also reported

The metrics used in the commute trip analysis include the average peak travel time the 95th percentile reliable travel time the duration of congestion and the percent of weekdays when average travel speeds are below 36 mph The performance of an individual route compares data with the current analysis year to the baseline year

WSDOTrsquos previously published person-based measures (per capita for statewide measures) include per person vehicle miles traveled and per person hours of delay in traffic (statewide urban area and corridor based) along with the per person trip travel time on commute corridors

WSDOT expanded reliability analysis looks at a range

WSDOT 2013 Corridor Capacity Report | 7

Introduction

Introduction

How do WSDOTrsquos congestion performance measures work

of travel time percentiles in the 2009 Congestion Report This analysis allows WSDOT to examine travel time changes at a finer level of detail and better evaluate its operational strategies

Real-time travel times for key commute routes in central and south Puget Sound areas Spokane and Vancouver are available to the public and updated every 5 minutes on the WSDOT website at www wsdotwagovtrafficseattletraveltimes

Measuring vehicle miles traveled (VMT) WSDOT examines vehicle miles traveled (VMT) as a volume metric for each commute route VMT is calculated for peak hours for the commute routes and all-day VMT is reported as part of the statewide metric WSDOT examines factors such as the use of public transportation population change unemployment rates real personal income and fuel prices as they relate to volume and travel time changes

VMT allows WSDOT to quantify travel along a route Because traffic volumes vary along a route each locationrsquos traffic volume is multiplied by the representative length of the route and these values are added up to obtain a routersquos total VMT WSDOT uses this measure to better understand the number of trips taken on certain commute routes and the total miles traveled on state highways This helps WSDOT predict future demand and establish improvement needs

Traffic volume is a vehicle count at a given roadway location It is measured by a detector in each lane at the location WSDOT has loop detectors spaced at roughly half-mile intervals throughout the central Puget Sound area freeway network and at various locations on the highway system statewide

WSDOT uses maximum throughput to measure congestion performance To operate the highway system as efficiently as possible the speed at which the highest number of vehicles can move through a highway segment (maximum throughput) is more meaningful than posted speed as the basis of measurement WSDOT aims to provide and maintain a system that yields the most productivity and efficiency rather than a system that is free flowing but where fewer vehicles can pass through a segment during peak travel periods

Understanding maximum throughput An adaptation of the Understanding maximum throughput An adaptation speedvolume curve of the speedvolume curveMay 2010 weekday volume 6-10 am I-405 NB at 24th NE I-405 northbound at 24th NE 6-10 am weekdays volume in May 2010Speed limit 60 mph Maximum throughput speed ranges between Speed limit 60 mph Maximum throughput speed ranges between70 and 85 of posted speed 70-85 of posted speed

When few vehicles use a70 mph highway they can all travel

0 mph

10 mph

20 mph

30 mph

40 mph

50 mph

60 mph near the speed limit

Maximum throughput

As still more vehicles use a highway all traffic slows and capacitydecreases

If more vehicles use a highway traffic slows but capacity remains high

If too many vehicles usea highway congestion greatly reduces capacity

0 500 1000 1500 2000 2500 Volume of vehicles per hour per lane

Data source WSDOT Northwest Region Traffic Office

Maximum throughput is achieved when vehicles travel at speeds between 42 and 51 mph (roughly 70 to 85 of a posted 60 mph speed) At maximum throughput speeds highways are operating at peak efficiency because more vehicles are passing through the segment than at posted speeds This happens because drivers at maximum throughput speeds can safely travel with a shorter distance between vehicles than they can at posted speeds

Maximum throughput speeds vary from one highway segment to the next depending on prevailing roadway design (roadway alignment lane width slope shoulder width pavement conditions presence or absence of median barriers) and traffic conditions (traffic composition conflicting traffic movements heavy truck traffic etc) The maximum throughput speed is not static and can change over time as conditions change Ideally maximum throughput speeds for each highway segment should be determined through comprehensive traffic studies and validated by field surveys For surface arterials (interrupted flow facilities) maximum throughput speeds are difficult to predict because they are influenced by interruptions in flow due to the conflicting traffic movements at intersections

WSDOT uses the maximum throughput standard as a basis for measurement to assess travel delay relative to a highwayrsquos most efficient condition at maximum throughput speeds (85 of posted speed) For more information on changes in travel delay performance please see pp 42-64

8 | WSDOT 2013 Corridor Capacity Report

Introduction

Introduction

WSDOT thresholds for system efficiency maximum throughput

WSDOT also uses maximum throughput as a basis for evaluating the system through the following measures

Total delay and per person delay

Percent of the system that is delayed and congested

Lost throughput productivity

Maximum Throughput Travel Time IndexmdashMT3I (for a more detailed discussion see p 46)

Duration of the congested period

Commute congestion cost

Measuring per person delay and total delay Delay can be measured at various speed thresholds such as free flow speed posted speed or maximum throughput speeds WSDOT uses maximum throughput speeds rather than free flow or posted speeds to measure delay relative to the highwayrsquos most efficient operating condition WSDOT measures travel delay statewide and on five major commute corridors in the central Puget Sound area In addition to measuring total hours of delay WSDOT also evaluates annual per person delay and the cost of delay to drivers and businesses

Measuring the percentage of the highway system that is delayed This measure allows WSDOT to assess the percentage of its system that is operating below maximum throughput speed creating delay for the traveling public The metric is

calculated for an average weekday by dividing the number of lane miles where speeds drop below 85 of posted speeds by total lane miles It allows differentiation between delayed lane miles in urban and rural areas of the state

Measuring the percentage of the highway system that is congested This measure allows WSDOT to evaluate what percentage of the system that the agency manages is congested It is calculated for an annual average weekday by dividing the number of lane miles where speeds drop below 70 of posted speeds by total lane miles This measure also differentiates between the portion of congested lane miles in urban versus rural areas of the state

Evaluating vehicle throughput productivity Highways are engineered to move specific volumes of vehicles based on the number of lanes and other design aspects Highways are not necessarily operating at their maximum efficiency when all vehicles are moving at 60 mph (the typical urban highway posted speed limit in Washington) As congestion increases speeds decrease and fewer vehicles pass through the corridor Throughput productivity may decline from a maximum of about 2000 vehicles per hour per lane traveling at speeds between 42 and 51 mph (100 efficiency) to as low as 700 vehicles per hour per lane (35 efficiency) at speeds less than 30 mph

WSDOT state highway speed thresholds for congestion measurement

Measure Threshold Description

Posted speed 60 mph Vehicles are moving through a highway segment at the posted speed but to travel safely at higher speeds and allow sufficient stopping distance drivers must maintain more space between vehicles Fewer vehicles can pass through the segment in a given amount of time and the segment is not operating at maximum efficiency

Maximum throughput speed (optimal flow speed)

70-85 of posted speed (about 42-51 mph)

Vehicles are moving slower than the posted speed and the number of vehicles moving through the highway segment is higher These speed conditions enable the segment to reach its maximum productivity in terms of vehicle volume and throughput (based on the speedvolume curve) This threshold range is used for highway system deficiency analysis

Duration of congested period (urban commute routes)

Duration of time vehicle speeds drop below 75 of posted speeds (45 mph)

The average weekday peak time period (in minutes) when average vehicle speeds drop below 75 of posted speeds (about 45 mph) Drivers have less than optimal spacing between cars and the number of vehicles that can move through a highway segment is reduced The highway begins to operate less efficiently under these conditions than at maximum throughput

Percent of state highway system delayed

Less than 85 of posted speeds

Percent of total state highway lane miles that drop below 85 of the posted speed limit

Percent of state highway system congested

Less than 70 of posted speeds

Percent of total state highway lane miles that drop below 70 of the posted speed limit

Severe congestion

Less than 60 of posted speed (less than 36 mph)

Speeds and spacing between vehicles continue to decline on a highway segment and highway efficiency operates well below maximum productivity

WSDOT 2013 Corridor Capacity Report | 9

Introduction

Introduction

Measuring per person delay vehicle throughput reliability

Measuring travel time reliability WSDOT uses the 95th percentile reliable travel time as its key reliability metric for the 82 commute trips monitored statewide Travel time reliability is measured in percentiles For example 95th percentile travel times track the amount of time a traveler will need to plan in order to be on time 95 of the time (19 of 20 weekday trips) 80th percentile travel times will ensure the traveler is on time four out of five weekday trips A benefit to using percentile measures is they are not affected by outlier values generally the longest travel times Using a range of percentiles ndash from the 50th (median) to the 95th ndash allows WSDOT to track changes in reliable travel times over the years at a finer level in order to evaluate operational improvements more accurately Changes in the 80th and 90th percentiles are likely to represent travel times that are the result of routine incidents and other factors that the agency can influence with

5

5

90 405

167

512

3

305

104

16

520

522

9

203

202

2

2

18

525

Seattle Bellevue

Everett

Tacoma

Renton

Kent

Auburn

Puyallup

Lakewood

Federal Way

Mukilteo

Poulsbo

Bremerton

Purdy

Fife

Redmond

509

Pierce County

Pierce County Kitsap County

King County

King County

Snohomish County

Kitsap Peninsula

Vashon Island

BainbridgeIsland

PugetSound

Lake Washington

WhidbeyIsland

Sea-Tac Intrsquol Airport

Tacoma Narrows Bridge

167

Snoh

omish

County

Island

County

5

104

3

Freeway HOV amp HOT Lane System

HOV lanes operate 24 hours HOV lanes operate 24 hours 3+ HOV lanes operate 5 am - 7 pm HOV lanes in Reversible Express Lane Roadway (variable hours) HOT lanes operate 5 am - 7 pm Construction funded Construction unfunded or partially funded Direct Access Ramps ndash Open Direct Access Ramps ndash Open(Transit Only) Direct Access Ramps ndash Future

NOTE HOV lanes require two or morepeople (2+) unless otherwise notedHours of operation are for all seven daysof the week

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Freeway HOV and HOT lane systems in the greater Puget Sound area

10 | WSDOT 2013 Corridor Capacity Report

operational strategies See pp 46-48 for detailed reliability data and pp 78-84 for more on operational strategies such as tolling Active Traffic Management Intelligent Transportation Systems (ITS) and Incident Response

WSDOT examines high occupancy vehicle (HOV) trip performance WSDOT uses several measures to evaluate HOV trip performance WSDOT and the Puget Sound Regional Council (PSRC) adopted a reliability standard for HOV lanes which states that for 90 of the peak hour HOV lanes should maintain an average speed of 45 mph This is the basis for WSDOTrsquos HOV reliability measure WSDOT also measures person throughput to gauge the effectiveness of HOV lanes in carrying more people compared to single occupancy vehicle (SOV) lanes and reports HOV trip travel times compared to SOV trip travel times

The map at left depicts the HOV and HOT lane system in the Puget Sound area About 310 lane-miles of the planned 320-mile Puget Sound area HOV network have been completed More information about the HOV lane network can be found starting on p 65 or at httpwwwwsdotwagovhov

Using Before and After analyses to review project performance As of June 30 2013 WSDOT completed 344 out of 421 projects funded by the 2003 and 2005 gas tax packages of which 91 were congestion relief projects To measure how well these investments are mitigating congestion WSDOT has implemented Before and After project studies to analyze impacts on travel times and delay On highway segments without in-pavement loop detectors data is collected using automated license plate recognition (ALPR) cameras blue tooth readers or moving test vehicles Before and After performance evaluations are performed on key congestion relief projects to evaluate the benefits of projects that improve system efficiency See pp 85-90

Quantifying Incident Response benefits WSDOT uses several measures to evaluate the performance of its Incident Response (IR) program Beginning in the 2011 Congestion Report WSDOT quantifies the annual economic benefits provided by the IR program For details on the IR program and how it helps alleviate non-recurrent congestion see pp 81-84